add help

36 files changed, 1150 insertions, 1203 deletions

diff --git a/src/rebar.app.src b/src/rebar.app.src
index 3164b73..c41ad92 100644
--- a/src/rebar.app.src
+++ b/src/rebar.app.src
@@ -21,22 +21,24 @@
         {log_level, warn},
 
         %% any_dir processing modules
-        {providers, [rebar_prv_escripter,
+        {providers, [rebar_prv_clean,
                      rebar_prv_deps,
                      rebar_prv_do,
                      rebar_prv_lock,
                      rebar_prv_install_deps,
                      rebar_prv_packages,
-                     rebar_erlydtl_compiler,
+                     rebar_prv_erlydtl_compiler,
                      rebar_prv_compile,
                      rebar_prv_app_discovery,
                      rebar_prv_shell,
                      rebar_prv_tar,
                      rebar_prv_new,
                      rebar_prv_update,
+                     rebar_prv_upgrade,
                      rebar_prv_release,
                      rebar_prv_version,
                      rebar_prv_common_test,
-                     rebar_prv_help]}
+                     rebar_prv_help,
+                     rebar_prv_test_deps]}
         ]}
  ]}.
diff --git a/src/rebar3.erl b/src/rebar3.erl
index dcd78f7..22c08ca 100644
--- a/src/rebar3.erl
+++ b/src/rebar3.erl
@@ -28,15 +28,16 @@
 
 -export([main/1,
          run/2,
-         option_spec_list/0,
+         global_option_spec_list/0,
+         init_config/0,
+         init_config1/1,
+         set_options/2,
          parse_args/1,
          version/0,
-         log_level/1]).
+         log_level/0]).
 
 -include("rebar.hrl").
 
--define(DEFAULT_JOBS, 3).
-
 %% ====================================================================
 %% Public API
 %% ====================================================================
@@ -44,14 +45,21 @@
 %% escript Entry point
 main(Args) ->
     case catch(run(Args)) of
-        ok ->
+        {ok, _State} ->
             ok;
         rebar_abort ->
             rebar_utils:delayed_halt(1);
+        {error, {Module, Reason}} ->
+            ?ERROR(Module:format_error(Reason, []), []),
+            rebar_utils:delayed_halt(1);
+        {error, Error} ->
+            ?ERROR(Error++"~n", []),
+            rebar_utils:delayed_halt(1);
         Error ->
             %% Nothing should percolate up from rebar_core;
             %% Dump this error to console
-            io:format("Uncaught error in rebar_core: ~p\n", [Error]),
+            ?ERROR("Uncaught error in rebar_core. Run with DEBUG=1 to see stacktrace~n", []),
+            ?DEBUG("Uncaught error: ~p~n", [Error]),
             rebar_utils:delayed_halt(1)
     end.
 
@@ -59,7 +67,7 @@ main(Args) ->
 run(BaseState, Command) ->
     _ = application:load(rebar),
     BaseState1 = rebar_state:set(BaseState, task, Command),
-    run_aux(BaseState1, []).
+    run_aux(BaseState1, [Command]).
 
 %% ====================================================================
 %% Internal functions
@@ -67,24 +75,21 @@ run(BaseState, Command) ->
 
 run(RawArgs) ->
     ok = load_rebar_app(),
-    %% Parse out command line arguments -- what's left is a list of commands to
-    %% run -- and start running commands
-    Args = parse_args(RawArgs),
-    BaseConfig = init_config(Args),
-    {BaseConfig1, Args1} = set_options(BaseConfig, Args),
-    run_aux(BaseConfig1, Args1).
+    BaseConfig = init_config(),
+    {BaseConfig1, _Args1} = set_options(BaseConfig, {[], []}),
+    run_aux(BaseConfig1, RawArgs).
 
 load_rebar_app() ->
     %% Pre-load the rebar app so that we get default configuration
     ok = application:load(rebar).
 
-init_config({Options, _NonOptArgs}) ->
+init_config() ->
     %% Initialize logging system
-    Verbosity = log_level(Options),
+    Verbosity = log_level(),
     ok = rebar_log:init(command_line, Verbosity),
 
-    Config = case proplists:get_value(config, Options) of
-                 undefined ->
+    Config = case os:getenv("REBAR_CONFIG") of
+                 false ->
                      rebar_config:consult_file(?DEFAULT_CONFIG_FILE);
                  ConfigFile ->
                      rebar_config:consult_file(ConfigFile)
@@ -103,8 +108,8 @@ init_config({Options, _NonOptArgs}) ->
                 true ->
                     ?DEBUG("Load global config file ~p~n",
                            [GlobalConfigFile]),
-                    rebar_config:consult_file(GlobalConfigFile),
-                    rebar_state:new(GlobalConfigFile, Config1);
+                    GlobalConfig = rebar_state:new(rebar_config:consult_file(GlobalConfigFile)),
+                    rebar_state:new(GlobalConfig, Config1);
                 false ->
                     rebar_state:new(Config1)
             end,
@@ -123,7 +128,7 @@ init_config1(BaseConfig) ->
             BaseConfig
     end.
 
-run_aux(State, Args) ->
+run_aux(State, RawArgs) ->
     %% Make sure crypto is running
     case crypto:start() of
         ok -> ok;
@@ -136,28 +141,33 @@ run_aux(State, Args) ->
 
     State1 = init_config1(State),
 
+    code:add_pathsa([filename:join(rebar_utils:get_cwd(), "plugins")]),
     %% Process each command, resetting any state between each one
     State2 = rebar_state:set(State1, base_dir, filename:absname(rebar_state:dir(State1))),
     {ok, Providers} = application:get_env(rebar, providers),
-    State3 = rebar_state:create_logic_providers(Providers, State2),
-    Task = rebar_state:get(State3, task, "help"),
-    rebar_core:process_command(rebar_state:command_args(State3, Args), list_to_atom(Task)),
-    ok.
+
+    {ok, PluginProviders, State3} = rebar_plugins:install(State2),
+    rebar_core:update_code_path(State3),
+
+    State4 = rebar_state:create_logic_providers(Providers++PluginProviders, State3),
+    {Task, Args} = parse_args(RawArgs),
+
+    rebar_core:process_command(rebar_state:command_args(State4, Args), list_to_atom(Task)).
 
 %%
 %% Parse command line arguments using getopt and also filtering out any
 %% key=value pairs. What's left is the list of commands to run
 %%
-parse_args(RawArgs) ->
-    %% Parse getopt options
-    OptSpecList = option_spec_list(),
-    case getopt:parse(OptSpecList, RawArgs) of
-        {ok, Args} ->
-            Args;
-        {error, {Reason, Data}} ->
-            ?ERROR("~s ~p~n~n", [Reason, Data]),
-            rebar_utils:delayed_halt(1)
-    end.
+parse_args([]) ->
+    parse_args(["help"]);
+parse_args([H | Rest]) when H =:= "-h"
+                          ; H =:= "--help" ->
+    parse_args(["help" | Rest]);
+parse_args([H | Rest]) when H =:= "-v"
+                          ; H =:= "--version" ->
+    parse_args(["version" | Rest]);
+parse_args([RawTask | RawRest]) ->
+    {RawTask, RawRest}.
 
 set_options(State, {Options, NonOptArgs}) ->
     GlobalDefines = proplists:get_all_values(defines, Options),
@@ -166,32 +176,26 @@ set_options(State, {Options, NonOptArgs}) ->
 
     %% Set global variables based on getopt options
     State2 = set_global_flag(State1, Options, force),
-    State3 = case proplists:get_value(jobs, Options, ?DEFAULT_JOBS) of
-                 ?DEFAULT_JOBS ->
-                     State2;
-                 Jobs ->
-                     rebar_state:set(State2, jobs, Jobs)
-             end,
 
     Task = proplists:get_value(task, Options, "help"),
 
-    {rebar_state:set(State3, task, Task), NonOptArgs}.
+    {rebar_state:set(State2, task, Task), NonOptArgs}.
 
 %%
 %% get log level based on getopt option
 %%
-log_level(Options) ->
-    case proplists:get_bool(quiet, Options) of
-        true ->
-            rebar_log:error_level();
+log_level() ->
+    case os:getenv("QUIET") of
         false ->
             DefaultLevel = rebar_log:default_level(),
-            case proplists:get_all_values(verbose, Options) of
-                [] ->
+            case os:getenv("DEBUG") of
+                false ->
                     DefaultLevel;
-                Verbosities ->
-                    DefaultLevel + lists:last(Verbosities)
-            end
+                _ ->
+                    DefaultLevel + 3
+            end;
+         _ ->
+            rebar_log:error_level()
     end.
 
 %%
@@ -218,17 +222,12 @@ set_global_flag(State, Options, Flag) ->
 %%
 %% options accepted via getopt
 %%
-option_spec_list() ->
-    Jobs = ?DEFAULT_JOBS,
-    JobsHelp = io_lib:format(
-                 "Number of concurrent workers a command may use. Default: ~B",
-                 [Jobs]),
+global_option_spec_list() ->
     [
-     %% {Name, ShortOpt, LongOpt, ArgSpec, HelpMsg}
-     {help,     $h, "help",     undefined, "Print this help."},
-     {verbose,  $v, "verbose",  integer,   "Verbosity level (-v, -vv)."},
-     {version,  $V, "version",  undefined, "Show version information."},
-     {jobs,     $j, "jobs",     integer,   JobsHelp},
-     {config,   $C, "config",   string,    "Rebar config file to use."},
-     {task,     undefined, undefined, string, "Task to run."}
+    %% {Name, ShortOpt, LongOpt, ArgSpec, HelpMsg}
+    {help,     $h, "help",     undefined, "Print this help."},
+    %{verbose,  $v, "verbose",  integer,   "Verbosity level (-v, -vv)."},
+    {version,  $V, "version",  undefined, "Show version information."},
+    %{config,   $C, "config",   string,    "Rebar config file to use."},
+    {task,     undefined, undefined, string, "Task to run."}
     ].
diff --git a/src/rebar_app_discover.erl b/src/rebar_app_discover.erl
index c90a8df..ae4916e 100644
--- a/src/rebar_app_discover.erl
+++ b/src/rebar_app_discover.erl
@@ -13,7 +13,8 @@ do(State, LibDirs) ->
     Apps = find_apps(Dirs, all),
     ProjectDeps = rebar_state:deps_names(State),
     lists:foldl(fun(AppInfo, StateAcc) ->
-                        rebar_state:project_apps(StateAcc, rebar_app_info:deps(AppInfo, ProjectDeps))
+                        ProjectDeps1 = lists:delete(rebar_app_info:name(AppInfo), ProjectDeps),
+                        rebar_state:project_apps(StateAcc, rebar_app_info:deps(AppInfo, ProjectDeps1))
             end, State, Apps).
 
 -spec all_app_dirs(list(file:name())) -> list(file:name()).
@@ -47,14 +48,17 @@ app_dirs(LibDir) ->
 find_unbuilt_apps(LibDirs) ->
     find_apps(LibDirs, invalid).
 
+-spec find_apps([file:filename_all()]) -> [rebar_app_info:t()].
 find_apps(LibDirs) ->
     find_apps(LibDirs, valid).
 
+-spec find_apps([file:filename_all()], valid | invalid | all) -> [rebar_app_info:t()].
 find_apps(LibDirs, Validate) ->
     rebar_utils:filtermap(fun(AppDir) ->
                                   find_app(AppDir, Validate)
                           end, all_app_dirs(LibDirs)).
 
+-spec find_app(file:filename_all(), valid | invalid | all) -> {true, rebar_app_info:t()} | false.
 find_app(AppDir, Validate) ->
     AppFile = filelib:wildcard(filename:join([AppDir, "ebin", "*.app"])),
     AppSrcFile = filelib:wildcard(filename:join([AppDir, "src", "*.app.src"])),
@@ -104,12 +108,17 @@ find_app(AppDir, Validate) ->
 app_dir(AppFile) ->
     filename:join(rebar_utils:droplast(filename:split(filename:dirname(AppFile)))).
 
+-spec create_app_info(file:name(), file:name()) -> rebar_app_info:t() | error.
 create_app_info(AppDir, AppFile) ->
     case file:consult(AppFile) of
         {ok, [{application, AppName, AppDetails}]} ->
             AppVsn = proplists:get_value(vsn, AppDetails),
+            %AppDeps = proplists:get_value(applications, AppDetails, []),
+            C = rebar_config:consult(AppDir),
+            S = rebar_state:new(rebar_state:new(), C, AppDir),
+            AppDeps = rebar_state:deps_names(S),
             AbsCwd = filename:absname(rebar_utils:get_cwd()),
-            {ok, AppInfo} = rebar_app_info:new(AppName, AppVsn, AppDir),
+            {ok, AppInfo} = rebar_app_info:new(AppName, AppVsn, AppDir, AppDeps),
             RebarConfig = filename:join(AppDir, "rebar.config"),
             AppState = case filelib:is_file(RebarConfig) of
                             true ->
@@ -121,22 +130,28 @@ create_app_info(AppDir, AppFile) ->
             AppState1 = rebar_state:set(AppState, base_dir, AbsCwd),
             AppInfo1 = rebar_app_info:config(
                          rebar_app_info:app_details(AppInfo, AppDetails), AppState1),
-            rebar_app_info:dir(AppInfo1, AppDir)
+            rebar_app_info:dir(AppInfo1, AppDir);
+        _ ->
+            error
     end.
 
 -spec validate_application_info(rebar_app_info:t()) -> boolean().
 validate_application_info(AppInfo) ->
     EbinDir = rebar_app_info:ebin_dir(AppInfo),
-    AppFile = rebar_app_info:app_file(AppInfo),
-    AppDetail = rebar_app_info:app_details(AppInfo),
-    case get_modules_list(AppFile, AppDetail) of
-        {ok, List} ->
-            has_all_beams(EbinDir, List);
-        _Error ->
-            false
+    case rebar_app_info:app_file(AppInfo) of
+        undefined ->
+            false;
+        AppFile ->
+            AppDetail = rebar_app_info:app_details(AppInfo),
+            case get_modules_list(AppFile, AppDetail) of
+                {ok, List} ->
+                    has_all_beams(EbinDir, List);
+                _Error ->
+                    false
+            end
     end.
 
--spec get_modules_list(file:name(), proplists:proplist()) ->
+-spec get_modules_list(file:filename_all(), proplists:proplist()) ->
                               {ok, list()} |
                               {warning, Reason::term()} |
                               {error, Reason::term()}.
@@ -148,8 +163,7 @@ get_modules_list(AppFile, AppDetail) ->
             {ok, ModulesList}
     end.
 
--spec has_all_beams(file:name(), list()) ->
-                           ok | {error, Reason::term()}.
+-spec has_all_beams(file:filename_all(), list()) -> boolean().
 has_all_beams(EbinDir, [Module | ModuleList]) ->
     BeamFile = filename:join([EbinDir,
                               ec_cnv:to_list(Module) ++ ".beam"]),
diff --git a/src/rebar_app_info.erl b/src/rebar_app_info.erl
index 008bfd2..7a33811 100644
--- a/src/rebar_app_info.erl
+++ b/src/rebar_app_info.erl
@@ -1,7 +1,6 @@
 -module(rebar_app_info).
 
--export([new/0,
-         new/1,
+-export([new/1,
          new/2,
          new/3,
          new/4,
@@ -21,6 +20,8 @@
          ebin_dir/1,
          deps/1,
          deps/2,
+         dep_level/1,
+         dep_level/2,
          dir/1,
          dir/2,
          source/1,
@@ -31,43 +32,40 @@
 -export_type([t/0]).
 
 -record(app_info_t, {name :: binary(),
-                     app_file_src :: file:name() | undefined,
-                     app_file :: file:name(),
-                     config :: rebar_config:config() | undefined,
-                     original_vsn :: string(),
+                     app_file_src :: file:filename_all() | undefined,
+                     app_file :: file:filename_all() | undefined,
+                     config :: rebar_state:t() | undefined,
+                     original_vsn :: binary() | string() | undefined,
                      app_details=[] :: list(),
                      deps=[] :: list(),
+                     dep_level :: integer(),
                      dir :: file:name(),
-                     source :: string() | undefined,
+                     source :: string() | tuple() | undefined,
                      valid :: boolean()}).
 
 %%============================================================================
 %% types
 %%============================================================================
--opaque t() :: record(app_info_t).
+-type t() :: record(app_info_t).
 
 %%============================================================================
 %% API
 %% ============================================================================
 %% @doc Build a new, empty, app info value. This is not of a lot of use and you
 %% probably wont be doing this much.
--spec new() -> {ok, t()}.
-new() ->
-    {ok, #app_info_t{}}.
-
 -spec new(atom() | binary() | string()) ->
                  {ok, t()}.
 new(AppName) ->
     {ok, #app_info_t{name=ec_cnv:to_binary(AppName)}}.
 
--spec new(atom() | binary() | string(), string()) ->
+-spec new(atom() | binary() | string(), binary() | string()) ->
                  {ok, t()}.
 new(AppName, Vsn) ->
     {ok, #app_info_t{name=ec_cnv:to_binary(AppName),
                      original_vsn=Vsn}}.
 
 %% @doc build a complete version of the app info with all fields set.
--spec new(atom() | binary() | string(), string(), file:name()) ->
+-spec new(atom() | binary() | string(), binary() | string(), file:name()) ->
                  {ok, t()}.
 new(AppName, Vsn, Dir) ->
     {ok, #app_info_t{name=ec_cnv:to_binary(AppName),
@@ -75,7 +73,7 @@ new(AppName, Vsn, Dir) ->
                      dir=Dir}}.
 
 %% @doc build a complete version of the app info with all fields set.
--spec new(atom() | binary() | string(), string(), file:name(), list()) ->
+-spec new(atom() | binary() | string(), binary() | string(), file:name(), list()) ->
                  {ok, t()}.
 new(AppName, Vsn, Dir, Deps) ->
     {ok, #app_info_t{name=ec_cnv:to_binary(AppName),
@@ -84,17 +82,16 @@ new(AppName, Vsn, Dir, Deps) ->
                      deps=Deps}}.
 
 %% @doc discover a complete version of the app info with all fields set.
--spec discover(file:name()) ->
-                 {ok, t()}.
+-spec discover(file:filename_all()) -> {ok, t()} | not_found.
 discover(Dir) ->
     case rebar_app_discover:find_app(Dir, all) of
         {true, AppInfo} ->
             {ok, AppInfo};
-        _ ->
+        false ->
             not_found
     end.
 
--spec name(t()) -> atom().
+-spec name(t()) -> binary().
 name(#app_info_t{name=Name}) ->
     Name.
 
@@ -102,15 +99,15 @@ name(#app_info_t{name=Name}) ->
 name(AppInfo=#app_info_t{}, AppName) ->
     AppInfo#app_info_t{name=ec_cnv:to_binary(AppName)}.
 
--spec config(t()) -> rebar_config:confg().
+-spec config(t()) -> rebar_state:t().
 config(#app_info_t{config=Config}) ->
     Config.
 
--spec config(t(), rebar_config:confg()) -> t().
+-spec config(t(), rebar_state:t()) -> t().
 config(AppInfo=#app_info_t{}, Config) ->
     AppInfo#app_info_t{config=Config}.
 
--spec app_file_src(t()) -> file:name().
+-spec app_file_src(t()) -> file:filename_all() | undefined.
 app_file_src(#app_info_t{app_file_src=undefined, dir=Dir, name=Name}) ->
     AppFileSrc = filename:join([ec_cnv:to_list(Dir), "src", ec_cnv:to_list(Name)++".app.src"]),
     case filelib:is_file(AppFileSrc) of
@@ -122,11 +119,11 @@ app_file_src(#app_info_t{app_file_src=undefined, dir=Dir, name=Name}) ->
 app_file_src(#app_info_t{app_file_src=AppFileSrc}) ->
     ec_cnv:to_list(AppFileSrc).
 
--spec app_file_src(t(), file:name()) -> t().
+-spec app_file_src(t(), file:filename_all()) -> t().
 app_file_src(AppInfo=#app_info_t{}, AppFileSrc) ->
     AppInfo#app_info_t{app_file_src=ec_cnv:to_list(AppFileSrc)}.
 
--spec app_file(t()) -> file:name().
+-spec app_file(t()) -> file:filename_all() | undefined.
 app_file(#app_info_t{app_file=undefined, dir=Dir, name=Name}) ->
     AppFile = filename:join([ec_cnv:to_list(Dir), "ebin", ec_cnv:to_list(Name)++".app"]),
     case filelib:is_file(AppFile) of
@@ -138,9 +135,9 @@ app_file(#app_info_t{app_file=undefined, dir=Dir, name=Name}) ->
 app_file(#app_info_t{app_file=AppFile}) ->
     AppFile.
 
--spec app_file(t(), file:name()) -> t().
+-spec app_file(t(), file:filename_all()) -> t().
 app_file(AppInfo=#app_info_t{}, AppFile) ->
-    AppInfo#app_info_t{app_file=ec_cnv:to_list(AppFile)}.
+    AppInfo#app_info_t{app_file=AppFile}.
 
 -spec app_details(t()) -> list().
 app_details(#app_info_t{app_details=AppDetails}) ->
@@ -154,7 +151,7 @@ app_details(AppInfo=#app_info_t{}, AppDetails) ->
 original_vsn(#app_info_t{original_vsn=Vsn}) ->
     Vsn.
 
--spec original_vsn(t(), string()) -> string().
+-spec original_vsn(t(), string()) -> t().
 original_vsn(AppInfo=#app_info_t{}, Vsn) ->
     AppInfo#app_info_t{original_vsn=Vsn}.
 
@@ -166,6 +163,12 @@ deps(#app_info_t{deps=Deps}) ->
 deps(AppInfo=#app_info_t{}, Deps) ->
     AppInfo#app_info_t{deps=Deps}.
 
+dep_level(AppInfo=#app_info_t{}, Level) ->
+    AppInfo#app_info_t{dep_level=Level}.
+
+dep_level(#app_info_t{dep_level=Level}) ->
+    Level.
+
 -spec dir(t()) -> file:name().
 dir(#app_info_t{dir=Dir}) ->
     Dir.
@@ -178,11 +181,11 @@ dir(AppInfo=#app_info_t{}, Dir) ->
 ebin_dir(#app_info_t{dir=Dir}) ->
     filename:join(Dir, "ebin").
 
--spec source(t(), string()) -> t().
+-spec source(t(), string() | tuple()) -> t().
 source(AppInfo=#app_info_t{}, Source) ->
     AppInfo#app_info_t{source=Source}.
 
--spec source(t()) -> string().
+-spec source(t()) -> string() | tuple().
 source(#app_info_t{source=Source}) ->
     Source.
 
diff --git a/src/rebar_app_utils.erl b/src/rebar_app_utils.erl
index 1c53743..8fc3df8 100644
--- a/src/rebar_app_utils.erl
+++ b/src/rebar_app_utils.erl
@@ -26,13 +26,14 @@
 %% -------------------------------------------------------------------
 -module(rebar_app_utils).
 
--export([is_app_dir/0, is_app_dir/1,
+-export([find/2,
+         find/3,
+         is_app_dir/0, is_app_dir/1,
          is_app_src/1,
          app_src_to_app/1,
          app_name/2,
          app_applications/2,
-         app_vsn/2,
-         is_skipped_app/2]).
+         app_vsn/2]).
 
 -export([load_app_file/2]). % TEMPORARY
 
@@ -42,9 +43,22 @@
 %% Public API
 %% ===================================================================
 
+-spec find(binary(), [rebar_app_info:t()]) -> {ok, rebar_app_info:t()} | error.
+find(Name, Apps) ->
+    ec_lists:find(fun(App) -> rebar_app_info:name(App) =:= Name end, Apps).
+
+-spec find(binary(), binary(), [rebar_app_info:t()]) -> {ok, rebar_app_info:t()} | error.
+find(Name, Vsn, Apps) ->
+    ec_lists:find(fun(App) ->
+                          rebar_app_info:name(App) =:= Name
+                              andalso rebar_app_info:original_vsn(App) =:= Vsn
+                  end, Apps).
+
+-spec is_app_dir() -> {true, file:name()} | false.
 is_app_dir() ->
     is_app_dir(rebar_utils:get_cwd()).
 
+-spec is_app_dir(file:name()) -> {true, file:name()} | false.
 is_app_dir(Dir) ->
     SrcDir = filename:join([Dir, "src"]),
     AppSrc = filename:join([SrcDir, "*.app.src"]),
@@ -109,30 +123,6 @@ app_vsn(Config, AppFile) ->
                    [AppFile, Reason])
     end.
 
-is_skipped_app(Config, AppFile) ->
-    {Config1, ThisApp} = app_name(Config, AppFile),
-    %% Check for apps global parameter; this is a comma-delimited list
-    %% of apps on which we want to run commands
-    Skipped =
-        case get_apps(Config) of
-            undefined ->
-                %% No apps parameter specified, check the skip_apps list..
-                case get_skip_apps(Config) of
-                    undefined ->
-                        %% No skip_apps list, run everything..
-                        false;
-                    SkipApps ->
-                        TargetApps = [list_to_atom(A) ||
-                                         A <- string:tokens(SkipApps, ",")],
-                        is_skipped(ThisApp, TargetApps)
-                end;
-            Apps ->
-                %% run only selected apps
-                TargetApps = [list_to_atom(A) || A <- string:tokens(Apps, ",")],
-                is_selected(ThisApp, TargetApps)
-        end,
-    {Config1, Skipped}.
-
 %% ===================================================================
 %% Internal functions
 %% ===================================================================
@@ -176,27 +166,3 @@ get_value(Key, AppInfo, AppFile) ->
         Value ->
             Value
     end.
-
-%% apps= for selecting apps
-is_selected(ThisApp, TargetApps) ->
-    case lists:member(ThisApp, TargetApps) of
-        false ->
-            {true, ThisApp};
-        true ->
-            false
-    end.
-
-%% skip_apps= for filtering apps
-is_skipped(ThisApp, TargetApps) ->
-    case lists:member(ThisApp, TargetApps) of
-        false ->
-            false;
-        true ->
-            {true, ThisApp}
-    end.
-
-get_apps(Config) ->
-    rebar_config:get_global(Config, apps, undefined).
-
-get_skip_apps(Config) ->
-    rebar_config:get_global(Config, skip_apps, undefined).
diff --git a/src/rebar_config.erl b/src/rebar_config.erl
index a45bef9..7ef2488 100644
--- a/src/rebar_config.erl
+++ b/src/rebar_config.erl
@@ -35,11 +35,11 @@
 %% Public API
 %% ===================================================================
 
--spec consult(file:name()) -> {ok, any()}.
+-spec consult(file:name()) -> [any()].
 consult(Dir) ->
     consult_file(filename:join(Dir, ?DEFAULT_CONFIG_FILE)).
 
--spec consult_file(file:name()) -> {ok, any()}.
+-spec consult_file(file:name()) -> [any()].
 consult_file(File) when is_binary(File) ->
     consult_file(binary_to_list(File));
 consult_file(File) ->
@@ -73,7 +73,6 @@ remove_script_ext(F) ->
 try_consult(File) ->
     case file:consult(File) of
         {ok, Terms} ->
-            ?DEBUG("Consult config file ~p~n", [File]),
             Terms;
         {error, enoent} ->
             [];
diff --git a/src/rebar_core.erl b/src/rebar_core.erl
index cb021e3..16d8f07 100644
--- a/src/rebar_core.erl
+++ b/src/rebar_core.erl
@@ -26,33 +26,61 @@
 %% -------------------------------------------------------------------
 -module(rebar_core).
 
--export([process_command/2]).
+-export([process_command/2
+        ,update_code_path/1]).
 
 -include("rebar.hrl").
 
+-spec process_command(rebar_state:t(), atom()) -> {ok, rebar_state:t()} | {error, string()}.
 process_command(State, Command) ->
+    %% ? rebar_prv_install_deps:setup_env(State),
+    Providers = rebar_state:providers(State),
+    TargetProviders = providers:get_target_providers(Command, Providers),
+    case providers:get_provider(Command, Providers) of
+        not_found ->
+            {error, io_lib:format("Command ~p not found", [Command])};
+        CommandProvider ->
+            Opts = providers:opts(CommandProvider)++rebar3:global_option_spec_list(),
+            case Command of
+                do ->
+                    do(TargetProviders, State);
+                _ ->
+                    case getopt:parse(Opts, rebar_state:command_args(State)) of
+                        {ok, Args} ->
+                            State2 = rebar_state:command_parsed_args(State, Args),
+                            do(TargetProviders, State2);
+                        {error, {invalid_option, Option}} ->
+                            {error, io_lib:format("Invalid option ~s on task ~p", [Option, Command])}
+                    end
+            end
+    end.
+
+-spec do([atom()], rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do([], State) ->
+    {ok, State};
+do([ProviderName | Rest], State) ->
+    Provider = providers:get_provider(ProviderName
+                                     ,rebar_state:providers(State)),
+    case providers:do(Provider, State) of
+        {ok, State1} ->
+            do(Rest, State1);
+        {error, Error} ->
+            {error, Error}
+    end.
+
+update_code_path(State) ->
     true = rebar_utils:expand_code_path(),
     LibDirs = rebar_state:get(State, lib_dirs, ?DEFAULT_LIB_DIRS),
-    DepsDir = rebar_state:get(State, deps_dir, ?DEFAULT_DEPS_DIRS),
-    _UpdatedCodePaths = update_code_path([DepsDir | LibDirs]),
-    rebar_prv_install_deps:setup_env(State),
-
-    TargetProviders = rebar_provider:get_target_providers(Command, State),
+    DepsDir = rebar_state:get(State, deps_dir, ?DEFAULT_DEPS_DIR),
+    PluginsDir = rebar_state:get(State, plugins_dir, ?DEFAULT_PLUGINS_DIR),
+    _UpdatedCodePaths = update_code_path_([DepsDir, PluginsDir | LibDirs]).
 
-    lists:foldl(fun(TargetProvider, Conf) ->
-                        Provider = rebar_provider:get_provider(TargetProvider
-                                                              ,rebar_state:providers(Conf)),
-                        {ok, Conf1} = rebar_provider:do(Provider, Conf),
-                        Conf1
-                end, State, TargetProviders).
 
 %% ===================================================================
 %% Internal functions
 %% ===================================================================
 
-update_code_path([]) ->
-    no_change;
-update_code_path(Paths) ->
+update_code_path_(Paths) ->
     LibPaths = expand_lib_dirs(Paths, rebar_utils:get_cwd(), []),
     ok = code:add_pathsa(LibPaths),
     %% track just the paths we added, so we can remove them without
diff --git a/src/rebar_erlc_compiler.erl b/src/rebar_erlc_compiler.erl
index 6a16977..33983e4 100644
--- a/src/rebar_erlc_compiler.erl
+++ b/src/rebar_erlc_compiler.erl
@@ -96,30 +96,30 @@ compile(Config, Dir) ->
     rebar_base_compiler:run(Config,
                             check_files(rebar_state:get(
                                           Config, xrl_first_files, [])),
-                            "src", ".xrl", "src", ".erl",
+                            filename:join(Dir, "src"), ".xrl", filename:join(Dir, "src"), ".erl",
                             fun compile_xrl/3),
     rebar_base_compiler:run(Config,
                             check_files(rebar_state:get(
                                           Config, yrl_first_files, [])),
-                            "src", ".yrl", "src", ".erl",
+                            filename:join(Dir, "src"), ".yrl", filename:join(Dir, "src"), ".erl",
                             fun compile_yrl/3),
     rebar_base_compiler:run(Config,
                             check_files(rebar_state:get(
                                           Config, mib_first_files, [])),
-                            "mibs", ".mib", "priv/mibs", ".bin",
+                            filename:join(Dir, "mibs"), ".mib", filename:join([Dir, "priv", "mibs"]), ".bin",
                             fun compile_mib/3),
     doterl_compile(Config, Dir).
 
 -spec clean(rebar_state:t(), file:filename()) -> 'ok'.
-clean(Config, _AppFile) ->
-    MibFiles = rebar_utils:find_files("mibs", ?RE_PREFIX".*\\.mib\$"),
+clean(Config, AppDir) ->
+    MibFiles = rebar_utils:find_files(filename:join(AppDir, "mibs"), ?RE_PREFIX".*\\.mib\$"),
     MIBs = [filename:rootname(filename:basename(MIB)) || MIB <- MibFiles],
     rebar_file_utils:delete_each(
-      [filename:join(["include",MIB++".hrl"]) || MIB <- MIBs]),
+      [filename:join([AppDir, "include",MIB++".hrl"]) || MIB <- MIBs]),
     lists:foreach(fun(F) -> ok = rebar_file_utils:rm_rf(F) end,
-                  ["ebin/*.beam", "priv/mibs/*.bin"]),
+                  [filename:join(AppDir, "ebin/*.beam"), filename:join(AppDir, "priv/mibs/*.bin")]),
 
-    YrlFiles = rebar_utils:find_files("src", ?RE_PREFIX".*\\.[x|y]rl\$"),
+    YrlFiles = rebar_utils:find_files(filename:join(AppDir, "src"), ?RE_PREFIX".*\\.[x|y]rl\$"),
     rebar_file_utils:delete_each(
       [ binary_to_list(iolist_to_binary(re:replace(F, "\\.[x|y]rl$", ".erl")))
         || F <- YrlFiles ]),
@@ -131,9 +131,9 @@ clean(Config, _AppFile) ->
     %% directory structure in ebin with .beam files within. As such, we want
     %% to scan whatever is left in the ebin/ directory for sub-dirs which
     %% satisfy our criteria.
-    BeamFiles = rebar_utils:find_files("ebin", ?RE_PREFIX".*\\.beam\$"),
+    BeamFiles = rebar_utils:find_files(filename:join(AppDir, "ebin"), ?RE_PREFIX".*\\.beam\$"),
     rebar_file_utils:delete_each(BeamFiles),
-    lists:foreach(fun(Dir) -> delete_dir(Dir, dirs(Dir)) end, dirs("ebin")),
+    lists:foreach(fun(Dir) -> delete_dir(Dir, dirs(Dir)) end, dirs(filename:join(AppDir, "ebin"))),
     ok.
 
 %% ===================================================================
@@ -241,14 +241,14 @@ test_compile_config_and_opts(Config, ErlOpts, Cmd) ->
     %% *_first_files is questionable as the file would need to exist
     %% in all project directories for it to work.
     OptsAtom = list_to_atom(Cmd ++ "_compile_opts"),
-    TestOpts = rebar_state:get_list(Config3, OptsAtom, []),
+    TestOpts = rebar_state:get(Config3, OptsAtom, []),
     Opts0 = [{d, 'TEST'}] ++
         ErlOpts ++ TestOpts ++ TriqOpts ++ PropErOpts ++ EqcOpts,
     Opts = [O || O <- Opts0, O =/= no_debug_info],
     Config4 = rebar_state:set(Config3, erl_opts, Opts),
 
     FirstFilesAtom = list_to_atom(Cmd ++ "_first_files"),
-    FirstErls = rebar_state:get_list(Config4, FirstFilesAtom, []),
+    FirstErls = rebar_state:get(Config4, FirstFilesAtom, []),
     Config5 = rebar_state:set(Config4, erl_first_files, FirstErls),
     {Config5, Opts}.
 
@@ -274,7 +274,7 @@ define_if(Def, true) -> [{d, Def}];
 define_if(_Def, false) -> [].
 
 is_lib_avail(Config, DictKey, Mod, Hrl, Name) ->
-    case rebar_state:get_xconf(Config, DictKey, undefined) of
+    case rebar_state:get(Config, DictKey, undefined) of
         undefined ->
             IsAvail = case code:lib_dir(Mod, include) of
                           {error, bad_name} ->
@@ -282,17 +282,17 @@ is_lib_avail(Config, DictKey, Mod, Hrl, Name) ->
                           Dir ->
                               filelib:is_regular(filename:join(Dir, Hrl))
                       end,
-            NewConfig = rebar_state:set_xconf(Config, DictKey, IsAvail),
+            NewConfig = rebar_state:set(Config, DictKey, IsAvail),
             ?DEBUG("~s availability: ~p\n", [Name, IsAvail]),
             {NewConfig, IsAvail};
         IsAvail ->
             {Config, IsAvail}
     end.
 
--spec doterl_compile(rebar_state:t(), file:filename()) -> 'ok'.
-doterl_compile(Config, Dir) ->
-    ErlOpts = rebar_utils:erl_opts(Config),
-    doterl_compile(Config, Dir, [], ErlOpts).
+-spec doterl_compile(rebar_state:t(), file:filename()) -> ok.
+doterl_compile(State, Dir) ->
+    ErlOpts = rebar_utils:erl_opts(State),
+    doterl_compile(State, Dir, [], ErlOpts).
 
 doterl_compile(Config, Dir, MoreSources, ErlOpts) ->
     OutDir = filename:join(Dir, "ebin"),
@@ -634,16 +634,19 @@ compile_yrl(Source, Target, Config) ->
 -spec compile_xrl_yrl(rebar_state:t(), file:filename(),
                       file:filename(), list(), module()) -> 'ok'.
 compile_xrl_yrl(Config, Source, Target, Opts, Mod) ->
+    Dir = rebar_state:dir(Config),
+    Opts1 = [{includefile, filename:join(Dir, I)} || {includefile, I} <- Opts,
+                                                     filename:pathtype(I) =:= relative],
     case needs_compile(Source, Target, []) of
         true ->
-            case Mod:file(Source, Opts ++ [{return, true}]) of
+            case Mod:file(Source, Opts1 ++ [{return, true}]) of
                 {ok, _} ->
                     ok;
                 {ok, _Mod, Ws} ->
                     rebar_base_compiler:ok_tuple(Config, Source, Ws);
                 {error, Es, Ws} ->
                     rebar_base_compiler:error_tuple(Config, Source,
-                                                    Es, Ws, Opts)
+                                                    Es, Ws, Opts1)
             end;
         false ->
             skipped
diff --git a/src/rebar_fetch.erl b/src/rebar_fetch.erl
index 6b31f6c..0a90848 100644
--- a/src/rebar_fetch.erl
+++ b/src/rebar_fetch.erl
@@ -49,14 +49,16 @@ lock_source(_AppDir, Source) ->
 download_source(AppDir, Source) ->
     TmpDir = ec_file:insecure_mkdtemp(),
     AppDir1 = ec_cnv:to_list(AppDir),
+    ec_file:mkdir_p(AppDir1),
     case download_source_tmp(TmpDir, Source) of
         {ok, _} ->
-            ec_file:mkdir_p(AppDir1),
             ok = ec_file:copy(TmpDir, filename:absname(AppDir1), [recursive]);
         {tarball, File} ->
-            ok = erl_tar:extract(File, [{cwd,
-                                         (filename:dirname(filename:absname(AppDir1)))}
-                                        ,compressed])
+            ok = erl_tar:extract(File, [{cwd, TmpDir}
+                                        ,compressed]),
+            BaseName = filename:basename(AppDir1),
+            [FromDir] = filelib:wildcard(filename:join(TmpDir, BaseName++"-*")),
+            ec_file:copy(FromDir, AppDir1, [recursive])
     end.
 
 download_source_tmp(TmpDir, {p4, Url}) ->
diff --git a/src/rebar_packages.erl b/src/rebar_packages.erl
index 103d3a3..cd979fa 100644
--- a/src/rebar_packages.erl
+++ b/src/rebar_packages.erl
@@ -4,7 +4,7 @@
 
 -include("rebar.hrl").
 
--spec get_packages(rebar_state:t()) -> {list(), rlx_depsolver:t()}.
+-spec get_packages(rebar_state:t()) -> {rebar_dict(), rlx_depsolver:t()}.
 get_packages(State) ->
     RebarDir = rebar_state:get(State, global_rebar_dir, filename:join(os:getenv("HOME"), ".rebar")),
     PackagesFile = filename:join(RebarDir, "packages"),
@@ -12,12 +12,13 @@ get_packages(State) ->
         true ->
             try
                 {ok, Binary} = file:read_file(PackagesFile),
-                binary_to_term(Binary)
+                {Dict, Graph} = binary_to_term(Binary),
+                {Dict, Graph}
             catch
                 _:_ ->
                     ?ERROR("Bad packages index, try to fix with `rebar update`~n", []),
-                    {[], rlx_depsolver:new()}
+                    {dict:new(), rlx_depsolver:new_graph()}
             end;
         false ->
-            {[], rlx_depsolver:new()}
+            {dict:new(), rlx_depsolver:new_graph()}
     end.
diff --git a/src/rebar_plugins.erl b/src/rebar_plugins.erl
index 0fdbc6d..b180ede 100644
--- a/src/rebar_plugins.erl
+++ b/src/rebar_plugins.erl
@@ -3,10 +3,36 @@
 
 -module(rebar_plugins).
 
--export([]).
+-export([install/1]).
 
 -include("rebar.hrl").
 
 %% ===================================================================
 %% Public API
 %% ===================================================================
+
+install(State) ->
+    State1 = rebar_state:set(State, deps_dir, ?DEFAULT_PLUGINS_DIR),
+
+    Plugins = rebar_state:get(State1, plugins, []),
+    {ok, State2} = rebar_prv_install_deps:handle_deps(State1, Plugins),
+
+    Apps = rebar_state:get(State2, all_deps, []),
+    ToBuild = lists:dropwhile(fun rebar_app_info:valid/1, Apps),
+    lists:foreach(fun(AppInfo) ->
+                          C = rebar_config:consult(rebar_app_info:dir(AppInfo)),
+                          S = rebar_state:new(rebar_state:new(), C, rebar_app_info:dir(AppInfo)),
+                          rebar_prv_compile:build(S, AppInfo)
+                  end, ToBuild),
+
+    PluginProviders = plugin_providers(Plugins),
+    {ok, PluginProviders, rebar_state:set(State2, deps_dir, ?DEFAULT_DEPS_DIR)}.
+
+plugin_providers(Plugins) ->
+    lists:map(fun({Plugin, _, _}) when is_atom(Plugin) ->
+                      Plugin;
+                 ({Plugin, _}) when is_atom(Plugin) ->
+                      Plugin;
+                 (Plugin) when is_atom(Plugin) ->
+                      Plugin
+              end, Plugins).
diff --git a/src/rebar_provider.erl b/src/rebar_provider.erl
deleted file mode 100644
index e5d7520..0000000
--- a/src/rebar_provider.erl
+++ /dev/null
@@ -1,165 +0,0 @@
--module(rebar_provider).
-
-%% API
--export([new/2,
-         do/2,
-         impl/1,
-         get_provider/2,
-         get_target_providers/2,
-         help/1,
-         format/1]).
-
--export_type([t/0]).
-
--include("rebar.hrl").
-
-%%%===================================================================
-%%% Types
-%%%===================================================================
-
--opaque t() :: record(provider).
-
--type provider_name() :: atom().
-
--ifdef(have_callback_support).
-
--callback init(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
--callback do(rebar_state:t()) ->  {ok, rebar_state:t()} | relx:error().
-
--else.
-
-%% In the case where R14 or lower is being used to compile the system
-%% we need to export a behaviour info
--export([behaviour_info/1]).
--spec behaviour_info(atom()) -> [{atom(), arity()}] | undefined.
-behaviour_info(callbacks) ->
-    [{init, 1},
-     {do, 1}];
-behaviour_info(_) ->
-    undefined.
-
--endif.
-
-%%%===================================================================
-%%% API
-%%%===================================================================
-
-%% @doc create a new provider object from the specified module. The
-%% module should implement the provider behaviour.
-%%
-%% @param ModuleName The module name.
-%% @param State0 The current state of the system
--spec new(module(), rebar_state:t()) ->
-                 {ok, rebar_state:t()}.
-new(ModuleName, State0) when is_atom(ModuleName) ->
-    case code:which(ModuleName) of
-        non_existing ->
-            ?ERROR("Module ~p does not exist.", [ModuleName]);
-        _ ->
-            ModuleName:init(State0)
-    end.
-
-%% @doc Manipulate the state of the system, that new state
-%%
-%% @param Provider the provider object
-%% @param State the current state of the system
--spec do(Provider::t(), rebar_state:t()) ->
-                {ok, rebar_state:t()}.
-do(Provider, State) ->
-    {PreHooks, PostHooks} = rebar_state:hooks(State, Provider#provider.name),
-    {ok, State1} = run_hook_plugins(PreHooks, State),
-    {ok, State2} = (Provider#provider.provider_impl):do(State1),
-    run_hook_plugins(PostHooks, State2).
-
-run_hook_plugins(Hooks, State) ->
-    State1 = lists:foldl(fun(Hook, StateAcc) ->
-                                 {ok, StateAcc1} = rebar_provider:do(Hook, StateAcc),
-                                 StateAcc1
-                         end, State, Hooks),
-    {ok, State1}.
-
-%%% @doc get the name of the module that implements the provider
-%%% @param Provider the provider object
--spec impl(Provider::t()) -> module().
-impl(Provider) ->
-    Provider#provider.name.
-
-help(State) ->
-    Providers = rebar_state:providers(State),
-    Help = lists:sort([{ec_cnv:to_list(P#provider.name), P#provider.short_desc} || P <- Providers,
-                                                                                   P#provider.bare =/= true]),
-    Longest = lists:max([length(X) || {X, _} <- Help]),
-
-    lists:foreach(fun({Name, ShortDesc}) ->
-                          Length = length(Name),
-                          Spacing = lists:duplicate(Longest - Length + 8, " "),
-                          io:format("~s~s~s~n", [Name, Spacing, ShortDesc])
-                  end, Help).
-
-
-%% @doc print the provider module name
-%%
-%% @param T - The provider
-%% @return An iolist describing the provider
--spec format(t()) -> iolist().
-format(#provider{name=Name}) ->
-    atom_to_list(Name).
-
-get_target_providers(Target, State) ->
-    Providers = rebar_state:providers(State),
-    TargetProviders = lists:filter(fun(#provider{name=T}) when T =:= Target->
-                                           true;
-                                      (#provider{name=T}) ->
-                                           false
-                                   end, Providers),
-    process_deps(TargetProviders, Providers).
-
--spec get_provider(provider_name(), [t()]) -> t().
-get_provider(ProviderName, [Provider = #provider{name = ProviderName} | _]) ->
-    Provider;
-get_provider(ProviderName, [_ | Rest]) ->
-    get_provider(ProviderName, Rest);
-get_provider(_ProviderName, _) ->
-    [].
-
-process_deps([], _Providers) ->
-    [];
-process_deps(TargetProviders, Providers) ->
-    DepChain = lists:flatmap(fun(Provider) ->
-                                     {DC, _, _} = process_deps(Provider, Providers, []),
-                                     DC
-                             end, TargetProviders),
-    ['NONE' | Rest] =
-        reorder_providers(lists:flatten([{'NONE', P#provider.name} || P <- TargetProviders] ++ DepChain)),
-    Rest.
-
-process_deps(Provider, Providers, Seen) ->
-    case lists:member(Provider, Seen) of
-        true ->
-            {[], Providers, Seen};
-        false ->
-            Deps = Provider#provider.deps,
-            DepList = lists:map(fun(Dep) ->
-                                        {Dep, Provider#provider.name}
-                                end, Deps),
-            {NewDeps, _, NewSeen} =
-                lists:foldl(fun(Arg, Acc) ->
-                                    process_dep(Arg, Acc)
-                            end,
-                           {[], Providers, Seen}, Deps),
-            {[DepList | NewDeps], Providers, NewSeen}
-    end.
-
-process_dep(ProviderName, {Deps, Providers, Seen}) ->
-    Provider = get_provider(ProviderName, Providers),
-    {NewDeps, _, NewSeen} = process_deps(Provider, Providers, [ProviderName | Seen]),
-    {[Deps | NewDeps], Providers, NewSeen}.
-
-%% @doc Reorder the providers according to thier dependency set.
-reorder_providers(OProviderList) ->
-    case rebar_topo:sort(OProviderList) of
-        {ok, ProviderList} ->
-            ProviderList;
-        {cycle, _} ->
-            ?ERROR("There was a cycle in the provider list. Unable to complete build!", [])
-    end.
diff --git a/src/rebar_prv_app_discovery.erl b/src/rebar_prv_app_discovery.erl
index 897a38d..e2dcf23 100644
--- a/src/rebar_prv_app_discovery.erl
+++ b/src/rebar_prv_app_discovery.erl
@@ -3,10 +3,11 @@
 
 -module(rebar_prv_app_discovery).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -19,18 +20,22 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = true,
-                                                       deps = ?DEPS,
-                                                       example = "",
-                                                       short_desc = "",
-                                                       desc = "",
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, true},
+                                                               {deps, ?DEPS},
+                                                               {example, ""},
+                                                               {short_desc, ""},
+                                                               {desc, ""},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     LibDirs = rebar_state:get(State, lib_dirs, ?DEFAULT_LIB_DIRS),
     State1 = rebar_app_discover:do(State, LibDirs),
     {ok, State1}.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
diff --git a/src/rebar_prv_clean.erl b/src/rebar_prv_clean.erl
new file mode 100644
index 0000000..72b85dc
--- /dev/null
+++ b/src/rebar_prv_clean.erl
@@ -0,0 +1,44 @@
+%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 et
+
+-module(rebar_prv_clean).
+
+-behaviour(provider).
+
+-export([init/1,
+         do/1,
+         format_error/2]).
+
+-include("rebar.hrl").
+
+-define(PROVIDER, clean).
+-define(DEPS, [app_discovery]).
+
+%% ===================================================================
+%% Public API
+%% ===================================================================
+
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar clean"},
+                                                               {short_desc, "Remove compiled beam files from apps."},
+                                                               {desc, ""},
+                                                               {opts, []}])),
+    {ok, State1}.
+
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    ProjectApps = rebar_state:project_apps(State),
+    lists:foreach(fun(AppInfo) ->
+                          ?INFO("Cleaning out ~s...~n", [rebar_app_info:name(AppInfo)]),
+                          rebar_erlc_compiler:clean(State, ec_cnv:to_list(rebar_app_info:dir(AppInfo)))
+                  end, ProjectApps),
+    {ok, State}.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
diff --git a/src/rebar_prv_common_test.erl b/src/rebar_prv_common_test.erl
index b880d77..37d1920 100644
--- a/src/rebar_prv_common_test.erl
+++ b/src/rebar_prv_common_test.erl
@@ -6,6 +6,7 @@
 -behaviour(rebar_provider).
 
 -export([init/1,
+         format_error/2,
          do/1]).
 
 -include("rebar.hrl").
@@ -19,15 +20,15 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State,
-                                      #provider{name = ?PROVIDER,
-                                                provider_impl = ?MODULE,
-                                                bare = false,
-                                                deps = ?DEPS,
-                                                example = "rebar ct",
-                                                short_desc = "Run Common Tests",
-                                                desc = "",
-                                                opts = []}),
+    Provider = providers:create([{name, ?PROVIDER},
+                                 {module, ?MODULE},
+                                 {deps, ?DEPS},
+                                 {bare, false},
+                                 {example, "rebar ct"},
+                                 {short_desc, "Run Common Tests"},
+                                 {desc, ""},
+                                 {opts, ct_opts(State)}]),
+    State1 = rebar_state:add_provider(State, Provider),
     {ok, State1}.
 
 -spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
@@ -36,6 +37,106 @@ do(State) ->
     ct:run_test(Opts),
     {ok, State}.
 
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
+ct_opts(State) ->
+    DefaultTestDir = filename:join([rebar_state:dir(State), "test"]),
+    DefaultLogsDir = filename:join([rebar_state:dir(State), "logs"]),
+    [{dir, undefined, "dir", {string, DefaultTestDir}, help(dir)}, %% dir
+     {suite, undefined, "suite", string, help(suite)}, %% comma-seperated list
+     {group, undefined, "group", string, help(group)}, %% comma-seperated list
+     {testcase, undefined, "case", string, help(testcase)}, %% comma-seperated list
+     {spec, undefined, "spec", string, help(spec)}, %% comma-seperated list
+     {join_specs, undefined, "join_specs", boolean, help(join_specs)}, %% Boolean
+     {label, undefined, "label", string, help(label)}, %% String
+     {config, undefined, "config", string, help(config)}, %% comma-seperated list
+     {userconfig, undefined, "userconfig", string, help(userconfig)}, %% [{CallbackMod, CfgStrings}] | {CallbackMod, CfgStrings}
+     {allow_user_terms, undefined, "allow_user_terms", boolean, help(allow_user_terms)}, %% Bool
+     {logdir, undefined, "logdir", {string, DefaultLogsDir}, help(logdir)}, %% string
+     {logopts, undefined, "logopts", string, help(logopts)}, %% enum, no_nl | no_src
+     {verbosity, undefined, "verbosity", string, help(verbosity)}, %% Integer OR [{Category, VLevel}]
+     {silent_connections, undefined, "silent_connections", string,
+      help(silent_connections)}, % all OR %% comma-seperated list
+     {stylesheet, undefined, "stylesheet", string, help(stylesheet)}, %% file
+     {cover, undefined, "cover", string, help(cover)}, %% file
+     {cover_stop, undefined, "cover_stop", boolean, help(cover_stop)}, %% Boolean
+     {event_handler, undefined, "event_handler", string, help(event_handler)}, %% EH | [EH] WHERE EH atom() | {atom(), InitArgs} | {[atom()], InitArgs}
+     {include, undefined, "include", string, help(include)},
+     {abort_if_missing_suites, undefined, "abort_if_missing_suites", {boolean, true},
+      help(abort_if_missing_suites)}, %% boolean
+     {multiply_timetraps, undefined, "multiply_timetraps", integer,
+      help(multiply_timetraps)}, %% integer
+     {scale_timetraps, undefined, "scale_timetraps", boolean, help(scale_timetraps)}, %% Boolean
+     {create_priv_dir, undefined, "create_priv_dir", string, help(create_priv_dir)}, %% enum: auto_per_run | auto_per_tc | manual_per_tc
+     {repeat, undefined, "repeat", integer, help(repeat)}, %% integer
+     {duration, undefined, "duration", string, help(duration)}, % format: HHMMSS
+     {until, undefined, "until", string, help(until)}, %% format: YYMoMoDD[HHMMSS]
+     {force_stop, undefined, "force_stop", string, help(force_stop)}, % enum: skip_rest, bool
+     {basic_html, undefined, "basic_html", boolean, help(basic_html)}, %% Booloean
+     {ct_hooks, undefined, "ct_hooks", string, help(ct_hooks)} %% List: [CTHModule | {CTHModule, CTHInitArgs}] where CTHModule is atom CthInitArgs is term
+    ].
+
+help(dir) ->
+    "Test folder (default: test/)";
+help(suite) ->
+    "List of test suites to run";
+help(group) ->
+    "List of test groups to run";
+help(testcase) ->
+    "List of test cases to run";
+help(spec) ->
+    "List of test specs to run";
+help(join_specs) ->
+    ""; %% ??
+help(label) ->
+    "Test label";
+help(config) ->
+    "List of config files";
+help(allow_user_terms) ->
+    ""; %% ??
+help(logdir) ->
+    "Log folder";
+help(logopts) ->
+    ""; %% ??
+help(verbosity) ->
+    "Verbosity";
+help(silent_connections) ->
+    ""; %% ??
+help(stylesheet) ->
+    "Stylesheet to use for test results";
+help(cover) ->
+    "Cover file to use";
+help(cover_stop) ->
+    ""; %% ??
+help(event_handler) ->
+    "Event handlers to attach to the runner";
+help(include) ->
+    "Include folder";
+help(abort_if_missing_suites) ->
+    "Abort if suites are missing";
+help(multiply_timetraps) ->
+    ""; %% ??
+help(scale_timetraps) ->
+    ""; %% ??
+help(create_priv_dir) ->
+    ""; %% ??
+help(repeat) ->
+    "How often to repeat tests";
+help(duration) ->
+    "Max runtime (format: HHMMSS)";
+help(until) ->
+    "Run until (format: HHMMSS)";
+help(force_stop) ->
+    "Force stop after time";
+help(basic_html) ->
+    "Show basic HTML";
+help(ct_hooks) ->
+    "";
+help(userconfig) ->
+    "".
+
 build_options(State) ->
     Arguments = rebar_state:command_args(State),
     Opts = parse_args(Arguments, []),
diff --git a/src/rebar_prv_compile.erl b/src/rebar_prv_compile.erl
index d89a4b0..30611cd 100644
--- a/src/rebar_prv_compile.erl
+++ b/src/rebar_prv_compile.erl
@@ -1,9 +1,10 @@
 -module(rebar_prv_compile).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
          do/1,
+         format_error/2,
          build/2]).
 
 -include("rebar.hrl").
@@ -11,34 +12,48 @@
 -define(PROVIDER, compile).
 -define(DEPS, [lock]).
 
+-define(DEFAULT_JOBS, 3).
+
 %% ===================================================================
 %% Public API
 %% ===================================================================
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                        provider_impl = ?MODULE,
-                                                        bare = false,
-                                                        deps = ?DEPS,
-                                                        example = "rebar compile",
-                                                        short_desc = "Compile apps .app.src and .erl files.",
-                                                        desc = "",
-                                                        opts = []}),
+    JobsHelp = io_lib:format(
+                 "Number of concurrent workers the compiler may use. Default: ~B",
+                 [?DEFAULT_JOBS]),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar compile"},
+                                                               {short_desc, "Compile apps .app.src and .erl files."},
+                                                               {desc, ""},
+                                                               {opts, [
+                                                                      {jobs,     $j, "jobs",     integer,   JobsHelp}
+                                                                      ]}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
-    ProjectApps = rebar_state:project_apps(State),
-    Deps = rebar_state:get(State, deps_to_build, []),
+    {ok, State1} = handle_args(State),
+
+    ProjectApps = rebar_state:project_apps(State1),
+    Deps = rebar_state:get(State1, deps_to_build, []),
 
     lists:foreach(fun(AppInfo) ->
-                          C = rebar_config:consult(rebar_app_info:dir(AppInfo)),
-                          S = rebar_state:new(rebar_state:new(), C, rebar_app_info:dir(AppInfo)),
+                          AppDir = rebar_app_info:dir(AppInfo),
+                          C = rebar_config:consult(AppDir),
+                          S = rebar_state:new(State1, C, AppDir),
                           build(S, AppInfo)
                   end, Deps++ProjectApps),
 
-    {ok, State}.
+    {ok, State1}.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
 
 build(State, AppInfo) ->
     ?INFO("Compiling ~s~n", [rebar_app_info:name(AppInfo)]),
@@ -49,3 +64,8 @@ build(State, AppInfo) ->
 %% ===================================================================
 %% Internal functions
 %% ===================================================================
+
+handle_args(State) ->
+    {Args, _} = rebar_state:command_parsed_args(State),
+    Jobs = proplists:get_value(jobs, Args, ?DEFAULT_JOBS),
+    {ok, rebar_state:set(State, jobs, Jobs)}.
diff --git a/src/rebar_prv_deps.erl b/src/rebar_prv_deps.erl
index 111f32f..80122ac 100644
--- a/src/rebar_prv_deps.erl
+++ b/src/rebar_prv_deps.erl
@@ -1,9 +1,10 @@
 -module(rebar_prv_deps).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -12,20 +13,24 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = true,
-                                                       deps = ?DEPS,
-                                                       example = "rebar deps",
-                                                       short_desc = "List dependencies",
-                                                       desc = info("List dependencies"),
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, true},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar deps"},
+                                                               {short_desc, "List dependencies"},
+                                                               {desc, info("List dependencies")},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     {ok, State}.
 
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
 info(Description) ->
     io_lib:format("~s.~n"
                  "~n"
diff --git a/src/rebar_prv_do.erl b/src/rebar_prv_do.erl
index a2ac648..e66fdbd 100644
--- a/src/rebar_prv_do.erl
+++ b/src/rebar_prv_do.erl
@@ -3,10 +3,11 @@
 
 -module(rebar_prv_do).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -19,27 +20,30 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar3 do <task1>, <task2>, ...",
-                                                       short_desc = "Higher order provider for running multiple tasks in a sequence.",
-                                                       desc = "",
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar3 do <task1>, <task2>, ..."},
+                                                               {short_desc, "Higher order provider for running multiple tasks in a sequence."},
+                                                               {desc, ""},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     Tasks = args_to_tasks(rebar_state:command_args(State)),
-    State1 = lists:foldl(fun(TaskArgs, StateAcc) ->
+    lists:foldl(fun(TaskArgs, {ok, StateAcc}) ->
                                  [TaskStr | Args] = string:tokens(TaskArgs, " "),
                                  Task = list_to_atom(TaskStr),
                                  StateAcc1 = rebar_state:set(StateAcc, task, Task),
                                  StateAcc2 = rebar_state:command_args(StateAcc1, Args),
                                  rebar_core:process_command(StateAcc2, Task)
-                       end, State, Tasks),
-    {ok, State1}.
+                       end, {ok, State}, Tasks).
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
 
 args_to_tasks(Args) ->
     [string:strip(T) || T <- string:tokens(string:join(Args, " "), ",")].
diff --git a/src/rebar_erlydtl_compiler.erl b/src/rebar_prv_erlydtl_compiler.erl
index 88ee20f..8d80cdd 100644
--- a/src/rebar_erlydtl_compiler.erl
+++ b/src/rebar_prv_erlydtl_compiler.erl
@@ -92,12 +92,13 @@
 %%          {doc_root, "templates"}, {module_ext, ""}, {source_ext, ".html"}
 %%      ]
 %%   ]}.
--module(rebar_erlydtl_compiler).
+-module(rebar_prv_erlydtl_compiler).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 %% for internal use only
 -export([info/2]).
@@ -113,22 +114,23 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar erlydtl compile",
-                                                       short_desc = "Compile erlydtl templates.",
-                                                       desc = "",
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar erlydtl compile"},
+                                                               {short_desc, "Compile erlydtl templates."},
+                                                               {desc, ""},
+                                                               {opts, []}])),
     {ok, State1}.
 
 do(Config) ->
     MultiDtlOpts = erlydtl_opts(Config),
     OrigPath = code:get_path(),
-    true = code:add_path(rebar_utils:ebin_dir()),
+    %true = code:add_path(rebar_utils:ebin_dir()),
 
     Result = lists:foldl(fun(DtlOpts, _) ->
+                                 file:make_dir(option(out_dir, DtlOpts)),
                                  rebar_base_compiler:run(Config, [],
                                                          option(doc_root, DtlOpts),
                                                          option(source_ext, DtlOpts),
@@ -144,6 +146,10 @@ do(Config) ->
     true = code:set_path(OrigPath),
     {Result, Config}.
 
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
 %% ===================================================================
 %% Internal functions
 %% ===================================================================
@@ -230,24 +236,15 @@ do_compile(Config, Source, Target, DtlOpts) ->
     Opts = lists:ukeymerge(1, DtlOpts, Sorted),
     ?INFO("Compiling \"~s\" -> \"~s\" with options:~n    ~s~n",
         [Source, Target, io_lib:format("~p", [Opts])]),
-    case erlydtl:compile(Source,
-                         module_name(Target),
+    case erlydtl:compile_file(ec_cnv:to_list(Source),
+                         list_to_atom(module_name(Target)),
                          Opts) of
-        ok ->
-            ok;
         {ok, _Mod} ->
             ok;
         {ok, _Mod, Ws} ->
             rebar_base_compiler:ok_tuple(Config, Source, Ws);
-        {ok, _Mod, _Bin, Ws} ->
-            rebar_base_compiler:ok_tuple(Config, Source, Ws);
         error ->
             rebar_base_compiler:error_tuple(Config, Source, [], [], Opts);
-        {error, {_File, _Msgs} = Error} ->
-            rebar_base_compiler:error_tuple(Config, Source, [Error], [], Opts);
-        {error, Msg} ->
-            Es = [{Source, [{erlydtl_parser, Msg}]}],
-            rebar_base_compiler:error_tuple(Config, Source, Es, [], Opts);
         {error, Es, Ws} ->
             rebar_base_compiler:error_tuple(Config, Source, Es, Ws, Opts)
     end.
diff --git a/src/rebar_prv_escripter.erl b/src/rebar_prv_escripter.erl
deleted file mode 100644
index 418ac6c..0000000
--- a/src/rebar_prv_escripter.erl
+++ /dev/null
@@ -1,224 +0,0 @@
-%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
-%% ex: ts=4 sw=4 et
-%% -------------------------------------------------------------------
-%%
-%% rebar: Erlang Build Tools
-%%
-%% Copyright (c) 2009 Dave Smith (dizzyd@dizzyd.com)
-%%
-%% Permission is hereby granted, free of charge, to any person obtaining a copy
-%% of this software and associated documentation files (the "Software"), to deal
-%% in the Software without restriction, including without limitation the rights
-%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-%% copies of the Software, and to permit persons to whom the Software is
-%% furnished to do so, subject to the following conditions:
-%%
-%% The above copyright notice and this permission notice shall be included in
-%% all copies or substantial portions of the Software.
-%%
-%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-%% THE SOFTWARE.
-%% -------------------------------------------------------------------
--module(rebar_prv_escripter).
-
--behaviour(rebar_provider).
-
--export([init/1,
-         do/1]).
-
--export([escriptize/2,
-         clean/2]).
-
-%% for internal use only
--export([info/2]).
-
--include("rebar.hrl").
--include_lib("kernel/include/file.hrl").
-
--define(PROVIDER, escriptize).
--define(DEPS, [app_builder]).
-
-%% ===================================================================
-%% Public API
-%% ===================================================================
-
--spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
-init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                        provider_impl = ?MODULE,
-                                                        bare = false,
-                                                        deps = ?DEPS,
-                                                        example = "rebar escriptize",
-                                                        short_desc = "Build escript from project.",
-                                                        desc = "",
-                                                        opts = []}),
-    {ok, State1}.
-
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
-do(Config) ->
-    AppName = rebar_state:get_local(Config, escript_top_level_app, undefined),
-    App = rebar_state:get_app(Config, AppName),
-    {ok, Config1} = escriptize(Config, rebar_app_info:app_file(App)),
-    {ok, Config1}.
-
-escriptize(Config0, AppFile) ->
-    %% Extract the application name from the archive -- this is the default
-    %% name of the generated script
-    {Config, AppName} = rebar_app_utils:app_name(Config0, AppFile),
-    AppNameStr = atom_to_list(AppName),
-
-    %% Get the output filename for the escript -- this may include dirs
-    Filename = rebar_state:get_local(Config, escript_name, AppName),
-    ok = filelib:ensure_dir(Filename),
-
-    %% Look for a list of other applications (dependencies) to include
-    %% in the output file. We then use the .app files for each of these
-    %% to pull in all the .beam files.
-    InclBeams = get_app_beams(
-                  rebar_state:get_local(Config, escript_incl_apps, []), []),
-
-    %% Look for a list of extra files to include in the output file.
-    %% For internal rebar-private use only. Do not use outside rebar.
-    InclExtra = get_extra(Config),
-
-    %% Construct the archive of everything in ebin/ dir -- put it on the
-    %% top-level of the zip file so that code loading works properly.
-    EbinPrefix = filename:join(AppNameStr, "ebin"),
-    EbinFiles = usort(load_files(EbinPrefix, "*", "ebin")),
-    ExtraFiles = usort(InclBeams ++ InclExtra),
-    Files = EbinFiles ++ ExtraFiles,
-
-    case zip:create("mem", Files, [memory]) of
-        {ok, {"mem", ZipBin}} ->
-            %% Archive was successfully created. Prefix that binary with our
-            %% header and write to our escript file
-            Shebang = rebar_state:get(Config, escript_shebang,
-                                       "#!/usr/bin/env escript\n"),
-            Comment = rebar_state:get(Config, escript_comment, "%%\n"),
-            DefaultEmuArgs = ?FMT("%%! -pa ~s/~s/ebin\n",
-                                  [AppNameStr, AppNameStr]),
-            EmuArgs = rebar_state:get(Config, escript_emu_args,
-                                       DefaultEmuArgs),
-            Script = iolist_to_binary([Shebang, Comment, EmuArgs, ZipBin]),
-            case file:write_file(Filename, Script) of
-                ok ->
-                    ok;
-                {error, WriteError} ->
-                    ?ERROR("Failed to write ~p script: ~p\n",
-                           [AppName, WriteError]),
-                    ?FAIL
-            end;
-        {error, ZipError} ->
-            ?ERROR("Failed to construct ~p escript: ~p\n",
-                   [AppName, ZipError]),
-            ?FAIL
-    end,
-
-    %% Finally, update executable perms for our script
-    {ok, #file_info{mode = Mode}} = file:read_file_info(Filename),
-    ok = file:change_mode(Filename, Mode bor 8#00111),
-    {ok, Config}.
-
-clean(Config0, AppFile) ->
-    %% Extract the application name from the archive -- this is the default
-    %% name of the generated script
-    {Config, AppName} = rebar_app_utils:app_name(Config0, AppFile),
-
-    %% Get the output filename for the escript -- this may include dirs
-    Filename = rebar_state:get_local(Config, escript_name, AppName),
-    rebar_file_utils:delete_each([Filename]),
-    {ok, Config}.
-
-%% ===================================================================
-%% Internal functions
-%% ===================================================================
-
-info(help, escriptize) ->
-    info_help("Generate escript archive");
-info(help, clean) ->
-    info_help("Delete generated escript archive").
-
-info_help(Description) ->
-    ?CONSOLE(
-       "~s.~n"
-       "~n"
-       "Valid rebar.config options:~n"
-       "  ~p~n"
-       "  ~p~n"
-       "  ~p~n"
-       "  ~p~n"
-       "  ~p~n",
-       [
-        Description,
-        {escript_name, "application"},
-        {escript_incl_apps, []},
-        {escript_shebang, "#!/usr/bin/env escript\n"},
-        {escript_comment, "%%\n"},
-        {escript_emu_args, "%%! -pa application/application/ebin\n"}
-       ]).
-
-get_app_beams([], Acc) ->
-    Acc;
-get_app_beams([App | Rest], Acc) ->
-    case code:lib_dir(App, ebin) of
-        {error, bad_name} ->
-            ?ABORT("Failed to get ebin/ directory for "
-                   "~p escript_incl_apps.", [App]);
-        Path ->
-            Prefix = filename:join(atom_to_list(App), "ebin"),
-            Acc2 = load_files(Prefix, "*", Path),
-            get_app_beams(Rest, Acc2 ++ Acc)
-    end.
-
-get_extra(Config) ->
-    Extra = rebar_state:get_local(Config, escript_incl_extra, []),
-    lists:foldl(fun({Wildcard, Dir}, Files) ->
-                        load_files(Wildcard, Dir) ++ Files
-                end, [], Extra).
-
-load_files(Wildcard, Dir) ->
-    load_files("", Wildcard, Dir).
-
-load_files(Prefix, Wildcard, Dir) ->
-    [read_file(Prefix, Filename, Dir)
-     || Filename <- filelib:wildcard(Wildcard, Dir)].
-
-read_file(Prefix, Filename, Dir) ->
-    Filename1 = case Prefix of
-                    "" ->
-                        Filename;
-                    _ ->
-                        filename:join([Prefix, Filename])
-                end,
-    [dir_entries(filename:dirname(Filename1)),
-     {Filename1, file_contents(filename:join(Dir, Filename))}].
-
-file_contents(Filename) ->
-    {ok, Bin} = file:read_file(Filename),
-    Bin.
-
-%% Given a filename, return zip archive dir entries for each sub-dir.
-%% Required to work around issues fixed in OTP-10071.
-dir_entries(File) ->
-    Dirs = dirs(File),
-    [{Dir ++ "/", <<>>} || Dir <- Dirs].
-
-%% Given "foo/bar/baz", return ["foo", "foo/bar", "foo/bar/baz"].
-dirs(Dir) ->
-    dirs1(filename:split(Dir), "", []).
-
-dirs1([], _, Acc) ->
-    lists:reverse(Acc);
-dirs1([H|T], "", []) ->
-    dirs1(T, H, [H]);
-dirs1([H|T], Last, Acc) ->
-    Dir = filename:join(Last, H),
-    dirs1(T, Dir, [Dir|Acc]).
-
-usort(List) ->
-    lists:ukeysort(1, lists:flatten(List)).
diff --git a/src/rebar_prv_help.erl b/src/rebar_prv_help.erl
index a9949e7..8300378 100644
--- a/src/rebar_prv_help.erl
+++ b/src/rebar_prv_help.erl
@@ -3,10 +3,11 @@
 
 -module(rebar_prv_help).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -19,30 +20,49 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar help <task>",
-                                                       short_desc = "Display a list of tasks or help for a given task or subtask.",
-                                                       desc = "",
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar help <task>"},
+                                                               {short_desc, "Display a list of tasks or help for a given task or subtask."},
+                                                               {desc, "Display a list of tasks or help for a given task or subtask."},
+                                                               {opts, [
+                                                                      {help_task, undefined, undefined, string, "Task to print help for."}
+                                                                      ]}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
-    help(State),
-    {ok, State}.
+    {Args, _} = rebar_state:command_parsed_args(State),
+    case proplists:get_value(help_task, Args, undefined) of
+        undefined ->
+            help(State),
+            {ok, State};
+        Name ->
+            Providers = rebar_state:providers(State),
+            case providers:get_provider(list_to_atom(Name), Providers) of
+                not_found ->
+                    {error, io_lib:format("Unknown task ~s", [Name])};
+                Provider ->
+                    providers:help(Provider),
+                    {ok, State}
+            end
+    end.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
 
 %%
 %% print help/usage string
 %%
 help(State) ->
     ?CONSOLE("Rebar is a tool for working with Erlang projects.~n~n", []),
-    OptSpecList = rebar3:option_spec_list(),
+    OptSpecList = rebar3:global_option_spec_list(),
     getopt:usage(OptSpecList, "rebar", "", []),
     ?CONSOLE("~nSeveral tasks are available:~n", []),
 
-    rebar_provider:help(State),
+    providers:help(rebar_state:providers(State)),
 
     ?CONSOLE("~nRun 'rebar help <TASK>' for details.~n~n", []).
diff --git a/src/rebar_prv_install_deps.erl b/src/rebar_prv_install_deps.erl
index d20f2b5..522420d 100644
--- a/src/rebar_prv_install_deps.erl
+++ b/src/rebar_prv_install_deps.erl
@@ -26,14 +26,16 @@
 %% -------------------------------------------------------------------
 -module(rebar_prv_install_deps).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
--export([setup_env/1]).
+-export([handle_deps/2,
+         handle_deps/3]).
 
 %% for internal use only
 -export([get_deps_dir/1]).
@@ -43,9 +45,9 @@
 -define(DEPS, [app_discovery]).
 
 -type src_dep() :: {atom(), string(), {atom(), string(), string()}}.
--type binary_dep() :: {atom(), binary()} | atom().
+-type pkg_dep() :: {atom(), binary()} | atom().
 
--type dep() :: src_dep() | binary_dep().
+-type dep() :: src_dep() | pkg_dep().
 
 %% ===================================================================
 %% Public API
@@ -53,174 +55,237 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = true,
-                                                       deps = ?DEPS,
-                                                       example = undefined,
-                                                       short_desc = "Install dependencies",
-                                                       desc = info("Install dependencies"),
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, true},
+                                                               {deps, ?DEPS},
+                                                               {example, undefined},
+                                                               {short_desc, "Install dependencies"},
+                                                               {desc, info("Install dependencies")},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
-    case rebar_state:get(State, locks, []) of
-        [] ->
-            handle_deps(State, ordsets:from_list(rebar_state:get(State, deps, [])));
-        Locks ->
-            handle_deps(State, ordsets:from_list(Locks))
+    ProjectApps = rebar_state:project_apps(State),
+    {ok, State1} = case rebar_state:get(State, locks, []) of
+                       [] ->
+                           handle_deps(State, rebar_state:get(State, deps, []));
+                       Locks ->
+                           handle_deps(State, Locks)
+                   end,
+
+    Source = ProjectApps ++ rebar_state:src_apps(State1),
+    case rebar_topo:sort_apps(Source) of
+        {ok, Sort} ->
+            {ok, rebar_state:set(State1, deps_to_build, lists:dropwhile(fun rebar_app_info:valid/1, Sort -- ProjectApps))};
+        {error, Error} ->
+            {error, Error}
     end.
 
-%% set REBAR_DEPS_DIR and ERL_LIBS environment variables
-setup_env(State) ->
-    DepsDir = get_deps_dir(State),
-    %% include rebar's DepsDir in ERL_LIBS
-    Separator = case os:type() of
-                    {win32, nt} ->
-                        ";";
-                    _ ->
-                        ":"
-                end,
-    ERL_LIBS = case os:getenv("ERL_LIBS") of
-                   false ->
-                       {"ERL_LIBS", DepsDir};
-                   PrevValue ->
-                       {"ERL_LIBS", DepsDir ++ Separator ++ PrevValue}
-               end,
-    [{"REBAR_DEPS_DIR", DepsDir}, ERL_LIBS].
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
 
 -spec get_deps_dir(rebar_state:t()) -> file:filename_all().
 get_deps_dir(State) ->
     BaseDir = rebar_state:get(State, base_dir, ""),
-    get_deps_dir(BaseDir, "deps").
+    DepsDir = rebar_state:get(State, deps_dir, ?DEFAULT_DEPS_DIR),
+    get_deps_dir(BaseDir, DepsDir).
 
--spec get_deps_dir(file:filename_all(), rebar_state:t()) -> file:filename_all().
+-spec get_deps_dir(file:filename_all(), file:filename_all()) -> file:filename_all().
 get_deps_dir(DepsDir, App) ->
     filename:join(DepsDir, App).
 
-%% ===================================================================
-%% Internal functions
-%% ===================================================================
-
 -spec handle_deps(rebar_state:t(), [dep()]) -> {ok, rebar_state:t()}.
-handle_deps(State, []) ->
-    {ok, State};
 handle_deps(State, Deps) ->
+    handle_deps(State, Deps, false).
+
+-spec handle_deps(rebar_state:t(), [dep()], boolean() | {true, binary(), integer()})
+                 -> {ok, rebar_state:t()}.
+handle_deps(State, [], _) ->
+    {ok, State};
+handle_deps(State, Deps, Update) ->
     %% Read in package index and dep graph
     {Packages, Graph} = rebar_packages:get_packages(State),
-    ProjectApps = rebar_state:project_apps(State),
 
-    %% Split source deps form binary deps, needed to keep backwards compatibility
+    %% Split source deps from pkg deps, needed to keep backwards compatibility
     DepsDir = get_deps_dir(State),
-    {SrcDeps, BinaryDeps} = parse_deps(DepsDir, Deps),
-    State1 = rebar_state:src_deps(rebar_state:binary_deps(State, BinaryDeps),
+    {SrcDeps, PkgDeps} = parse_deps(DepsDir, Deps),
+    State1 = rebar_state:src_deps(rebar_state:pkg_deps(State, PkgDeps),
                                   SrcDeps),
 
     %% Fetch transitive src deps
-    State2 = update_src_deps(State1),
-    Solved = case rebar_state:binary_deps(State2) of
-                 [] -> %% No binary deps
-                     [];
-                 BinaryDeps1 ->
-                     %% Find binary deps needed
-                     {ok, S} = rlx_depsolver:solve(Graph, BinaryDeps1),
-                     %% Create app_info record for each binary dep
-                     lists:map(fun({Name, Vsn}) ->
-                                       AppInfo = package_to_app(DepsDir
-                                                               ,Packages
-                                                               ,Name
-                                                               ,Vsn),
-                                       ok = maybe_fetch(AppInfo),
-                                       AppInfo
-                               end, S)
+    State2 = update_src_deps(0, State1, Update),
+    Solved = case rebar_state:pkg_deps(State2) of
+                 [] -> %% No pkg deps
+                      [];
+                 PkgDeps1 ->
+                     %% Find pkg deps needed
+                     {ok, S} = rlx_depsolver:solve(Graph, PkgDeps1),
+                     %% Create app_info record for each pkg dep
+                     [AppInfo || Pkg <- S,
+                                 AppInfo <- package_to_app(DepsDir
+                                                          ,Packages
+                                                          ,Pkg),
+                                 maybe_fetch(AppInfo, Update)]
              end,
 
-    Source = ProjectApps ++ ordsets:to_list(rebar_state:src_deps(State2)),
-    AllDeps = ordsets:union([ordsets:to_list(rebar_state:src_deps(State2))
-                            ,ordsets:from_list(Solved)]),
-
+    AllDeps = lists:ukeymerge(2
+                            ,lists:ukeysort(2, rebar_state:src_apps(State2))
+                            ,lists:ukeysort(2, Solved)),
     %% Sort all apps to build order
     State3 = rebar_state:set(State2, all_deps, AllDeps),
-    {ok, Sort} = rebar_topo:sort_apps(ordsets:to_list(Source)),
-    {ok, rebar_state:set(State3, deps_to_build, lists:dropwhile(fun is_valid/1, Sort -- ProjectApps))}.
+    {ok, State3}.
+
+%% ===================================================================
+%% Internal functions
+%% ===================================================================
 
--spec is_valid(rebar_app_info:t()) -> boolean().
-is_valid(App) ->
-    rebar_app_info:valid(App).
+package_to_app(DepsDir, Packages, Pkg={_, Vsn}) ->
+    Name = ec_cnv:to_binary(rlx_depsolver:dep_pkg(Pkg)),
+    FmtVsn = iolist_to_binary(rlx_depsolver:format_version(Vsn)),
+    case dict:find({Name, FmtVsn}, Packages) of
+        error ->
+            [];
+        {ok, P} ->
+            PkgDeps = proplists:get_value(<<"deps">>, P, []),
+            Link = proplists:get_value(<<"link">>, P, ""),
+            {ok, AppInfo} = rebar_app_info:new(Name, FmtVsn),
+            AppInfo1 = rebar_app_info:deps(AppInfo, PkgDeps),
+            AppInfo2 = rebar_app_info:dir(AppInfo1, get_deps_dir(DepsDir, Name)),
+            [rebar_app_info:source(AppInfo2, Link)]
+    end.
 
--spec package_to_app(file:name(), rlx_depsolver:t(), binary(), binary()) -> rebar_app_info:t().
-package_to_app(DepsDir, Packages, Name, Vsn) ->
-    FmtVsn = ec_cnv:to_binary(rlx_depsolver:format_version(Vsn)),
+-spec update_src_deps(integer(), rebar_state:t(), boolean()) -> rebar_state:t().
+update_src_deps(Level, State, Update) ->
+    SrcDeps = rebar_state:src_deps(State),
+    case lists:foldl(fun(AppInfo, {SrcDepsAcc, PkgDepsAcc, StateAcc}) ->
+                             case Update of
+                                 {true, UpdateName, UpdateLevel} ->
+                                     handle_update(AppInfo
+                                                  ,UpdateName
+                                                  ,UpdateLevel
+                                                  ,SrcDepsAcc
+                                                  ,PkgDepsAcc
+                                                  ,Level
+                                                  ,StateAcc);
+                                 _ ->
+                                     maybe_fetch(AppInfo, false),
+                                     handle_dep(AppInfo
+                                               ,SrcDepsAcc
+                                               ,PkgDepsAcc
+                                               ,Level
+                                               ,StateAcc)
+                             end
+                     end, {[], rebar_state:pkg_deps(State), State}, SrcDeps) of
+        {[], NewPkgDeps, State1} ->
+            rebar_state:pkg_deps(State1, NewPkgDeps);
+        {NewSrcDeps, NewPkgDeps, State1} ->
+            State2 = rebar_state:pkg_deps(State1, NewPkgDeps),
+            State3 = rebar_state:src_deps(State2, NewSrcDeps),
+            update_src_deps(Level+1, State3, Update)
+    end.
 
-    {ok, P} = dict:find({Name, FmtVsn}, Packages),
-    PkgDeps = proplists:get_value(<<"deps">>, P),
-    Link = proplists:get_value(<<"link">>, P),
+handle_update(AppInfo, UpdateName, UpdateLevel, SrcDeps, PkgDeps, Level, State) ->
+    Name = rebar_app_info:name(AppInfo),
+    Locks = rebar_state:get(State, locks, []),
+    {_, _, _, DepLevel} = lists:keyfind(Name, 1, Locks),
+    case UpdateLevel < DepLevel
+        orelse Name =:= UpdateName of
+        true ->
+            case maybe_fetch(AppInfo, true) of
+                true ->
+                    handle_dep(AppInfo
+                              ,SrcDeps
+                              ,PkgDeps
+                              ,Level
+                              ,State);
 
-    {ok, AppInfo} = rebar_app_info:new(Name, FmtVsn),
-    AppInfo1 = rebar_app_info:deps(AppInfo, PkgDeps),
-    AppInfo2 =
-        rebar_app_info:dir(AppInfo1, get_deps_dir(DepsDir, <<Name/binary, "-", FmtVsn/binary>>)),
-    rebar_app_info:source(AppInfo2, Link).
+                false ->
+                    {SrcDeps, PkgDeps, State}
+            end;
+        false ->
+            {SrcDeps, PkgDeps, State}
+    end.
 
--spec update_src_deps(rebar_state:t()) -> rebat_state:t().
-update_src_deps(State) ->
-    SrcDeps = rebar_state:src_deps(State),
+handle_dep(AppInfo, SrcDeps, PkgDeps, Level, State) ->
     DepsDir = get_deps_dir(State),
-    case lists:foldl(fun(AppInfo, {SrcDepsAcc, BinaryDepsAcc}) ->
-                             ok = maybe_fetch(AppInfo),
-                             {AppInfo1, NewSrcDeps, NewBinaryDeps} = handle_dep(DepsDir, AppInfo),
-                             {ordsets:union(ordsets:add_element(AppInfo1, SrcDepsAcc), NewSrcDeps)
-                             ,NewBinaryDeps++BinaryDepsAcc}
-                     end, {ordsets:new(), rebar_state:binary_deps(State)}, SrcDeps) of
-        {NewSrcDeps, NewBinaryDeps} when length(SrcDeps) =:= length(NewSrcDeps) ->
-            rebar_state:src_deps(rebar_state:binary_deps(State, NewBinaryDeps), NewSrcDeps);
-        {NewSrcDeps, NewBinaryDeps} ->
-            State1 = rebar_state:src_deps(rebar_state:binary_deps(State, NewBinaryDeps), NewSrcDeps),
-            update_src_deps(State1)
-    end.
+    {AppInfo1, NewSrcDeps, NewPkgDeps} =
+        handle_dep(DepsDir, AppInfo),
+    AppInfo2 = rebar_app_info:dep_level(AppInfo1, Level),
+    {NewSrcDeps ++ SrcDeps
+    ,NewPkgDeps++PkgDeps
+    ,rebar_state:src_apps(State, AppInfo2)}.
 
--spec handle_dep(binary(), rebar_state:t()) -> {[rebar_app_info:t()], [binary_dep()]}.
+-spec handle_dep(file:filename_all(), rebar_app_info:t()) ->
+                        {rebar_app_info:t(), [rebar_app_info:t()], [pkg_dep()]}.
 handle_dep(DepsDir, AppInfo) ->
     C = rebar_config:consult(rebar_app_info:dir(AppInfo)),
     S = rebar_state:new(rebar_state:new(), C, rebar_app_info:dir(AppInfo)),
     Deps = rebar_state:get(S, deps, []),
     AppInfo1 = rebar_app_info:deps(AppInfo, rebar_state:deps_names(S)),
-    {SrcDeps, BinaryDeps} = parse_deps(DepsDir, Deps),
-    {AppInfo1, SrcDeps, BinaryDeps}.
+    {SrcDeps, PkgDeps} = parse_deps(DepsDir, Deps),
+    {AppInfo1, SrcDeps, PkgDeps}.
 
--spec maybe_fetch(rebar_app_info:t()) -> ok.
-maybe_fetch(AppInfo) ->
-    AppDir = rebar_app_info:dir(AppInfo),
-    case filelib:is_dir(AppDir) of
-        false ->
-            ?INFO("Fetching ~s~n", [rebar_app_info:name(AppInfo)]),
-            Source = rebar_app_info:source(AppInfo),
-            rebar_fetch:download_source(AppDir, Source);
-        true ->
-            ok
+-spec maybe_fetch(rebar_app_info:t(), boolean() | {true, binary(), integer()}) -> boolean().
+maybe_fetch(AppInfo, Update) ->
+    AppDir = ec_cnv:to_list(rebar_app_info:dir(AppInfo)),
+    Apps = rebar_app_discover:find_apps(["_checkouts"], all),
+    case rebar_app_utils:find(rebar_app_info:name(AppInfo), Apps) of
+        {ok, _} ->
+            %% Don't fetch dep if it exists in the _checkouts dir
+            false;
+        error ->
+            Exists = case rebar_app_utils:is_app_dir(filename:absname(AppDir)++"-*") of
+                         {true, _} ->
+                             true;
+                         _ ->
+                             case rebar_app_utils:is_app_dir(filename:absname(AppDir)) of
+                                 {true, _} ->
+                                     true;
+                                 _ ->
+                                     false
+                             end
+                     end,
+
+            case not Exists orelse Update of
+                true ->
+                    ?INFO("Fetching ~s~n", [rebar_app_info:name(AppInfo)]),
+                    Source = rebar_app_info:source(AppInfo),
+                    rebar_fetch:download_source(AppDir, Source),
+                    true;
+                _ ->
+                    false
+            end
     end.
 
--spec parse_deps(binary(), [dep()]) -> {ordsets:ordset(rebar_app_info:t()), [binary_dep()]}.
+-spec parse_deps(binary(), [dep()]) -> {[rebar_app_info:t()], [pkg_dep()]}.
 parse_deps(DepsDir, Deps) ->
-    lists:foldl(fun({Name, Vsn}, {SrcDepsAcc, BinaryDepsAcc}) ->
+    lists:foldl(fun({Name, Vsn}, {SrcDepsAcc, PkgDepsAcc}) ->
                         {SrcDepsAcc, [parse_goal(ec_cnv:to_binary(Name)
-                                                ,ec_cnv:to_binary(Vsn)) | BinaryDepsAcc]};
-                   (Name, {SrcDepsAcc, BinaryDepsAcc}) when is_atom(Name) ->
-                        {SrcDepsAcc, [ec_cnv:to_binary(Name) | BinaryDepsAcc]};
-                   ({Name, Vsn, Source}, {SrcDepsAcc, BinaryDepsAcc}) when is_tuple (Source) ->
-                        Dir = ec_cnv:to_list(get_deps_dir(DepsDir, Name)),
-                        {ok, Dep} = case rebar_app_info:discover(Dir) of
-                                        {ok, App} ->
-                                            {ok, App};
-                                        not_found ->
-                                            rebar_app_info:new(Name, Vsn, Dir)
-                                    end,
-                        Dep1 = rebar_app_info:source(Dep, Source),
-                        {ordsets:add_element(Dep1, SrcDepsAcc), BinaryDepsAcc}
-                end, {ordsets:new(), []}, Deps).
-
--spec parse_goal(binary(), binary()) -> binary_dep().
+                                                ,ec_cnv:to_binary(Vsn)) | PkgDepsAcc]};
+                   (Name, {SrcDepsAcc, PkgDepsAcc}) when is_atom(Name) ->
+                        {SrcDepsAcc, [ec_cnv:to_binary(Name) | PkgDepsAcc]};
+                   ({Name, Vsn, Source}, {SrcDepsAcc, PkgDepsAcc}) when is_tuple (Source) ->
+                        Dep = new_dep(DepsDir, Name, Vsn, Source),
+                        {[Dep | SrcDepsAcc], PkgDepsAcc};
+                   ({Name, Vsn, Source, _Level}, {SrcDepsAcc, PkgDepsAcc}) when is_tuple (Source) ->
+                        Dep = new_dep(DepsDir, Name, Vsn, Source),
+                        {[Dep | SrcDepsAcc], PkgDepsAcc}
+                end, {[], []}, Deps).
+
+new_dep(DepsDir, Name, Vsn, Source) ->
+    Dir = ec_cnv:to_list(get_deps_dir(DepsDir, Name)),
+    {ok, Dep} = case rebar_app_info:discover(Dir) of
+                    {ok, App} ->
+                        {ok, App};
+                    not_found ->
+                        rebar_app_info:new(Name, Vsn, Dir)
+                end,
+    rebar_app_info:source(Dep, Source).
+
+-spec parse_goal(binary(), binary()) -> pkg_dep().
 parse_goal(Name, Constraint) ->
     case re:run(Constraint, "([^\\d]*)(\\d.*)", [{capture, [1,2], binary}]) of
         {match, [<<>>, Vsn]} ->
@@ -236,9 +301,7 @@ info(Description) ->
                  "~n"
                  "Valid rebar.config options:~n"
                  "  ~p~n"
-                 "  ~p~n"
-                 "Valid command line options:~n"
-                 "  deps_dir=\"deps\" (override default or rebar.config deps_dir)~n",
+                 "  ~p~n",
                  [
                  Description,
                  {deps_dir, "deps"},
diff --git a/src/rebar_prv_lock.erl b/src/rebar_prv_lock.erl
index b4a7d8d..32c5f1a 100644
--- a/src/rebar_prv_lock.erl
+++ b/src/rebar_prv_lock.erl
@@ -1,9 +1,10 @@
 -module(rebar_prv_lock).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -16,17 +17,17 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = true,
-                                                       deps = ?DEPS,
-                                                       example = "",
-                                                       short_desc = "Locks dependencies.",
-                                                       desc = info("Locks dependencies"),
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, true},
+                                                               {deps, ?DEPS},
+                                                               {example, ""},
+                                                               {short_desc, "Locks dependencies."},
+                                                               {desc, info("Locks dependencies")},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     case rebar_state:get(State, locks, []) of
         [] ->
@@ -40,7 +41,8 @@ do(State) ->
                                           Source when is_tuple(Source) ->
                                               {rebar_app_info:name(Dep)
                                               ,rebar_app_info:original_vsn(Dep)
-                                              ,rebar_fetch:lock_source(Dir, Source)};
+                                              ,rebar_fetch:lock_source(Dir, Source)
+                                              ,rebar_app_info:dep_level(Dep)};
                                           _Source ->
                                               {rebar_app_info:name(Dep)
                                               ,rebar_app_info:original_vsn(Dep)}
@@ -53,5 +55,9 @@ do(State) ->
             {ok, State}
     end.
 
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
 info(_) ->
     "".
diff --git a/src/rebar_prv_new.erl b/src/rebar_prv_new.erl
index ed3c1b4..2555b4d 100644
--- a/src/rebar_prv_new.erl
+++ b/src/rebar_prv_new.erl
@@ -1,9 +1,10 @@
 -module(rebar_prv_new).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -16,17 +17,17 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar new <template>",
-                                                       short_desc = "Create new project from templates.",
-                                                       desc = info(create),
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar new <template>"},
+                                                               {short_desc, "Create new project from templates."},
+                                                               {desc, info()},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     case rebar_state:command_args(State) of
         [TemplateName] ->
@@ -41,33 +42,17 @@ do(State) ->
             {ok, State}
     end.
 
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
 %% ===================================================================
 %% Internal functions
 %% ===================================================================
 
-info(create) ->
-    io_lib:format(
-       "Create skel based on template and vars.~n"
-       "~n"
-       "Valid command line options:~n"
-       "  template= [var=foo,...]~n", []);
-info(create_app) ->
-    io_lib:format(
-       "Create simple app skel.~n"
-       "~n"
-       "Valid command line options:~n"
-       "  [appid=myapp]~n", []);
-info(create_lib) ->
-    io_lib:format(
-       "Create simple lib skel.~n"
-       "~n"
-       "Valid command line options:~n"
-       "  [libid=mylib]~n", []);
-info(create_node) ->
+info() ->
     io_lib:format(
-       "Create simple node skel.~n"
-       "~n"
-       "Valid command line options:~n"
-       "  [nodeid=mynode]~n", []);
-info(list_templates) ->
-    io_lib:format("List available templates.~n", []).
+      "Create rebar project based on template and vars.~n"
+      "~n"
+      "Valid command line options:~n"
+      "  template= [var=foo,...]~n", []).
diff --git a/src/rebar_prv_packages.erl b/src/rebar_prv_packages.erl
index 79c1cd2..be51833 100644
--- a/src/rebar_prv_packages.erl
+++ b/src/rebar_prv_packages.erl
@@ -1,9 +1,10 @@
 -module(rebar_prv_packages).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -12,22 +13,26 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar pkgs",
-                                                       short_desc = "List available packages.",
-                                                       desc = info("List available packages"),
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar pkgs"},
+                                                               {short_desc, "List available packages."},
+                                                               {desc, info("List available packages")},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     {Packages, _Graph} = rebar_packages:get_packages(State),
     print_packages(Packages),
     {ok, State}.
 
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
 print_packages(Packages) ->
     Keys = lists:keysort(1, dict:fetch_keys(Packages)),
     Pkgs = merge(Keys),
diff --git a/src/rebar_prv_release.erl b/src/rebar_prv_release.erl
index 4203c3a..572f909 100644
--- a/src/rebar_prv_release.erl
+++ b/src/rebar_prv_release.erl
@@ -3,10 +3,11 @@
 
 -module(rebar_prv_release).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -19,17 +20,28 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar release",
-                                                       short_desc = "Build release of project.",
-                                                       desc = "",
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar release"},
+                                                               {short_desc, "Build release of project."},
+                                                               {desc, ""},
+                                                               {opts, relx:opt_spec_list()}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
-do(Config) ->
-    relx:main("release"),
-    {ok, Config}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    Options = rebar_state:command_args(State),
+    AllOptions = string:join(["release" | Options], " "),
+    case rebar_state:get(State, relx, []) of
+        [] ->
+            relx:main(AllOptions);
+        Config ->
+            relx:main([{config, Config}], AllOptions)
+    end,
+    {ok, State}.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
diff --git a/src/rebar_prv_shell.erl b/src/rebar_prv_shell.erl
index 80f6bcf..24e357b 100644
--- a/src/rebar_prv_shell.erl
+++ b/src/rebar_prv_shell.erl
@@ -28,10 +28,11 @@
 -module(rebar_prv_shell).
 -author("Kresten Krab Thorup <krab@trifork.com>").
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -44,21 +45,25 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                        provider_impl = ?MODULE,
-                                                        bare = false,
-                                                        deps = ?DEPS,
-                                                        example = "rebar shell",
-                                                        short_desc = "Run shell with project apps and deps in path.",
-                                                        desc = info(),
-                                                        opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar shell"},
+                                                               {short_desc, "Run shell with project apps and deps in path."},
+                                                               {desc, info()},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(Config) ->
     shell(),
     {ok, Config}.
 
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
 %% NOTE:
 %% this is an attempt to replicate `erl -pa ./ebin -pa deps/*/ebin`. it is
 %% mostly successful but does stop and then restart the user io system to get
diff --git a/src/rebar_prv_tar.erl b/src/rebar_prv_tar.erl
index 7f5ab4f..04a1b33 100644
--- a/src/rebar_prv_tar.erl
+++ b/src/rebar_prv_tar.erl
@@ -3,10 +3,11 @@
 
 -module(rebar_prv_tar).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -19,17 +20,26 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                        provider_impl = ?MODULE,
-                                                        bare = false,
-                                                        deps = ?DEPS,
-                                                        example = "rebar tar",
-                                                        short_desc = "Tar archive of release built of project.",
-                                                        desc = "",
-                                                        opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar tar"},
+                                                               {short_desc, "Tar archive of release built of project."},
+                                                               {desc, ""},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
-do(Config) ->
-    relx:main("release tar"),
-    {ok, Config}.
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    case rebar_state:get(State, relx, []) of
+        [] ->
+            relx:main(["release tar"]);
+        Config ->
+            relx:main([{config, Config}], ["release tar"])
+    end,
+    {ok, State}.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
diff --git a/src/rebar_prv_test_deps.erl b/src/rebar_prv_test_deps.erl
new file mode 100644
index 0000000..081b210
--- /dev/null
+++ b/src/rebar_prv_test_deps.erl
@@ -0,0 +1,63 @@
+-module(rebar_prv_test_deps).
+
+-behaviour(provider).
+
+-export([init/1,
+         do/1,
+         format_error/2]).
+
+-include("rebar.hrl").
+
+-define(PROVIDER, test_deps).
+-define(DEPS, [install_deps]).
+
+%% ===================================================================
+%% Public API
+%% ===================================================================
+
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    Providers = rebar_state:providers(State),
+    CompileProvider = providers:get_provider(compile, Providers),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, true},
+                                                               {deps, ?DEPS},
+                                                               {hooks, {[], [CompileProvider]}},
+                                                               {example, undefined},
+                                                               {short_desc, "Install dependencies needed only for testing."},
+                                                               {desc, ""},
+                                                               {opts, []}])),
+    {ok, State1}.
+
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    ProjectApps = rebar_state:project_apps(State),
+    TestDeps = rebar_state:get(State, test_deps, []),
+    Names = [ec_cnv:to_binary(element(1, Dep)) || Dep <- TestDeps],
+    ProjectApps1 = [rebar_app_info:deps(A, Names) || A <- ProjectApps],
+
+    {ok, State1} = rebar_prv_install_deps:handle_deps(State, TestDeps),
+    AllDeps = rebar_state:get(State1, all_deps, []),
+
+    case rebar_topo:sort_apps(ProjectApps1++AllDeps) of
+        {ok, Sort} ->
+            _ToBuild = lists:dropwhile(fun rebar_app_info:valid/1, Sort),
+            %% lists:foreach(fun(AppInfo) ->
+            %%                       AppDir = rebar_app_info:dir(AppInfo),
+            %%                       C = rebar_config:consult(AppDir),
+            %%                       S = rebar_state:new(State1, C, AppDir),
+            %%                       rebar_prv_compile:build(S, AppInfo)
+            %%               end, ToBuild),
+            {ok, State1};
+        {error, Error} ->
+            {error, Error}
+    end.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
+
+%% ===================================================================
+%% Internal functions
+%% ===================================================================
diff --git a/src/rebar_prv_update.erl b/src/rebar_prv_update.erl
index e19041a..0d388c8 100644
--- a/src/rebar_prv_update.erl
+++ b/src/rebar_prv_update.erl
@@ -3,10 +3,11 @@
 
 -module(rebar_prv_update).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -19,41 +20,35 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar update cowboy",
-                                                       short_desc = "Update package index or individual dependency.",
-                                                       desc = "",
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar update"},
+                                                               {short_desc, "Update package index."},
+                                                               {desc, ""},
+                                                               {opts, []}])),
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
-    case rebar_state:command_args(State) of
-        [Name] ->
-            ?ERROR("NOT IMPLEMENTED: Updating ~s~n", [Name]),
-            {ok, State};
-        [] ->
-            ?INFO("Updating package index...~n", []),
-            Url = url(State),
-            %{ok, [Home]} = init:get_argument(home),
-            ec_file:mkdir_p(filename:join([os:getenv("HOME"), ".rebar"])),
-            PackagesFile = filename:join([os:getenv("HOME"), ".rebar", "packages"]),
-            {ok, RequestId} = httpc:request(get, {Url, []}, [], [{stream, PackagesFile}, {sync, false}]),
-            wait(RequestId, State)
-    end.
-
-wait(RequestId, State) ->
-    receive
-        {http, {RequestId, saved_to_file}} ->
-            {ok, State}
-    after
-        500 ->
-            io:format("."),
-            wait(RequestId, State)
-    end.
+    ?INFO("Updating package index...~n", []),
+    try
+        Url = url(State),
+                                                %{ok, [Home]} = init:get_argument(home),
+        ec_file:mkdir_p(filename:join([os:getenv("HOME"), ".rebar"])),
+        PackagesFile = filename:join([os:getenv("HOME"), ".rebar", "packages"]),
+        {ok, _RequestId} = httpc:request(get, {Url, []}, [], [{stream, PackagesFile}
+                                                             ,{sync, true}])
+    catch
+        _:_ ->
+            {error, io_lib:format("Failed to write package index.~n", [])}
+    end,
+    {ok, State}.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
 
 url(State) ->
     SystemArch = erlang:system_info(system_architecture),
diff --git a/src/rebar_prv_upgrade.erl b/src/rebar_prv_upgrade.erl
new file mode 100644
index 0000000..1668e1c
--- /dev/null
+++ b/src/rebar_prv_upgrade.erl
@@ -0,0 +1,55 @@
+%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 et
+
+-module(rebar_prv_upgrade).
+
+-behaviour(provider).
+
+-export([init/1,
+         do/1,
+         format_error/2]).
+
+-include("rebar.hrl").
+
+-define(PROVIDER, upgrade).
+-define(DEPS, [lock]).
+
+%% ===================================================================
+%% Public API
+%% ===================================================================
+
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    State1 =
+        rebar_state:add_provider(State,
+                                 providers:create([{name, ?PROVIDER},
+                                                   {module, ?MODULE},
+                                                   {bare, false},
+                                                   {deps, ?DEPS},
+                                                   {example, "rebar upgrade cowboy"},
+                                                   {short_desc, "Upgrade dependency."},
+                                                   {desc, ""},
+                                                   {opts, [
+                                                          {package, undefined, undefined, string, "Package to upgrade."}
+                                                          ]}])),
+    {ok, State1}.
+
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    {Args, _} = rebar_state:command_parsed_args(State),
+    Name = proplists:get_value(package, Args),
+    ?INFO("Updating ~s~n", [Name]),
+    Locks = rebar_state:get(State, locks, []),
+    case lists:keyfind(ec_cnv:to_binary(Name), 1, Locks) of
+        {_, _, _, Level} ->
+            Deps = rebar_state:get(State, deps),
+            Dep = lists:keyfind(list_to_atom(Name), 1, Deps),
+            rebar_prv_install_deps:handle_deps(State, [Dep], {true, ec_cnv:to_binary(Name), Level}),
+            {ok, State};
+        _ ->
+            {error, io_lib:format("No such dependency ~s~n", [Name])}
+    end.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
diff --git a/src/rebar_prv_version.erl b/src/rebar_prv_version.erl
index 9197438..1e907d1 100644
--- a/src/rebar_prv_version.erl
+++ b/src/rebar_prv_version.erl
@@ -3,10 +3,11 @@
 
 -module(rebar_prv_version).
 
--behaviour(rebar_provider).
+-behaviour(provider).
 
 -export([init/1,
-         do/1]).
+         do/1,
+         format_error/2]).
 
 -include("rebar.hrl").
 
@@ -19,18 +20,22 @@
 
 -spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
 init(State) ->
-    State1 = rebar_state:add_provider(State, #provider{name = ?PROVIDER,
-                                                       provider_impl = ?MODULE,
-                                                       bare = false,
-                                                       deps = ?DEPS,
-                                                       example = "rebar version",
-                                                       short_desc = "Print version for rebar and current Erlang.",
-                                                       desc = "",
-                                                       opts = []}),
+    State1 = rebar_state:add_provider(State, providers:create([{name, ?PROVIDER},
+                                                               {module, ?MODULE},
+                                                               {bare, false},
+                                                               {deps, ?DEPS},
+                                                               {example, "rebar version"},
+                                                               {short_desc, "Print version for rebar and current Erlang."},
+                                                               {desc, ""},
+                                                               {opts, []}])),
 
     {ok, State1}.
 
--spec do(rebar_state:t()) -> {ok, rebar_state:t()} | relx:error().
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
 do(State) ->
     rebar3:version(),
     {ok, State}.
+
+-spec format_error(any(), rebar_state:t()) ->  {iolist(), rebar_state:t()}.
+format_error(Reason, State) ->
+    {io_lib:format("~p", [Reason]), State}.
diff --git a/src/rebar_state.erl b/src/rebar_state.erl
index 706c528..f39251d 100644
--- a/src/rebar_state.erl
+++ b/src/rebar_state.erl
@@ -3,49 +3,39 @@
 -export([new/0, new/1, new/2, new/3,
          get/2, get/3, set/3,
          command_args/1, command_args/2,
+         command_parsed_args/1, command_parsed_args/2,
 
          dir/1, dir/2,
-         set_skip_dir/2, is_skip_dir/2, reset_skip_dirs/1,
          create_logic_providers/2,
 
          project_apps/1, project_apps/2,
 
          deps_names/1,
-         binary_deps/1, binary_deps/2,
+         pkg_deps/1, pkg_deps/2,
          src_deps/1, src_deps/2,
+         src_apps/1, src_apps/2,
 
          prepend_hook/3, append_hook/3, hooks/2,
          providers/1, providers/2, add_provider/2]).
 
 -include("rebar.hrl").
 
--ifdef(namespaced_types).
-%% dict:dict() exists starting from Erlang 17.
--type rebar_dict() :: dict:dict(term(), term()).
--else.
-%% dict() has been obsoleted in Erlang 17 and deprecated in 18.
--type rebar_dict() :: dict().
--endif.
+-record(state_t, {dir :: file:name(),
+                  opts = [],
 
--record(state_t, {dir :: file:filename(),
-                  opts = [] :: list(),
-                  local_opts = [] :: list(),
-                  config = new_globals() :: rebar_dict(),
+                  command_args = [],
+                  command_parsed_args = [],
 
-                  envs = new_env() :: rebar_dict(),
-                  command_args = [] :: list(),
+                  src_deps = [],
+                  src_apps = [],
+                  pkg_deps = [] :: [rlx_depsolver:constraint()],
+                  project_apps = [],
 
-                  src_deps = ordsets:new() :: ordsets:ordset(rebar_app_info:t()),
-                  binary_deps = [],
-                  project_apps = ordsets:new() :: ordsets:ordset(rebar_app_info:t()),
-
-                  providers = [],
-                  hooks = [],
-                  skip_dirs = new_skip_dirs() :: rebar_dict() }).
+                  providers = []}).
 
 -export_type([t/0]).
 
--opaque t() :: #state_t{}.
+-type t() :: record(state_t).
 
 -spec new() -> t().
 new() ->
@@ -64,9 +54,9 @@ new(ParentState=#state_t{}, Config) ->
 
 -spec new(t(), list(), file:name()) -> t().
 new(ParentState, Config, Dir) ->
-    _Opts = ParentState#state_t.opts,
+    Opts = ParentState#state_t.opts,
     LocalOpts = case rebar_config:consult_file(?LOCK_FILE) of
-                    {ok, [D]} ->
+                    [D] ->
                         [{locks, D} | Config];
                     _ ->
                         Config
@@ -74,7 +64,7 @@ new(ParentState, Config, Dir) ->
 
     ProviderModules = [],
     create_logic_providers(ProviderModules, ParentState#state_t{dir=Dir
-                                                               ,opts=LocalOpts}).
+                                                               ,opts=lists:umerge(LocalOpts, Opts)}).
 
 get(State, Key) ->
     proplists:get_value(Key, State#state_t.opts).
@@ -82,33 +72,23 @@ get(State, Key) ->
 get(State, Key, Default) ->
     proplists:get_value(Key, State#state_t.opts, Default).
 
+-spec set(t(), any(), any()) -> t().
 set(State, Key, Value) ->
     Opts = proplists:delete(Key, State#state_t.opts),
     State#state_t { opts = [{Key, Value} | Opts] }.
 
-set_skip_dir(State, Dir) ->
-    OldSkipDirs = State#state_t.skip_dirs,
-    NewSkipDirs = case is_skip_dir(State, Dir) of
-                      false ->
-                          ?DEBUG("Adding skip dir: ~s\n", [Dir]),
-                          dict:store(Dir, true, OldSkipDirs);
-                      true ->
-                          OldSkipDirs
-                  end,
-    State#state_t{skip_dirs = NewSkipDirs}.
-
-is_skip_dir(State, Dir) ->
-    dict:is_key(Dir, State#state_t.skip_dirs).
-
-reset_skip_dirs(State) ->
-    State#state_t{skip_dirs = new_skip_dirs()}.
-
 command_args(#state_t{command_args=CmdArgs}) ->
     CmdArgs.
 
 command_args(State, CmdArgs) ->
     State#state_t{command_args=CmdArgs}.
 
+command_parsed_args(#state_t{command_parsed_args=CmdArgs}) ->
+    CmdArgs.
+
+command_parsed_args(State, CmdArgs) ->
+    State#state_t{command_parsed_args=CmdArgs}.
+
 dir(#state_t{dir=Dir}) ->
     Dir.
 
@@ -123,13 +103,14 @@ deps_names(State) ->
                       ec_cnv:to_binary(Dep)
               end, Deps).
 
-binary_deps(#state_t{binary_deps=BinaryDeps}) ->
-    BinaryDeps.
+-spec pkg_deps(t()) -> [rlx_depsolver:constraint()].
+pkg_deps(#state_t{pkg_deps=PkgDeps}) ->
+    PkgDeps.
 
-binary_deps(State=#state_t{binary_deps=BinaryDeps}, NewBinaryDeps) when is_list(BinaryDeps) ->
-    State#state_t{binary_deps=NewBinaryDeps};
-binary_deps(State=#state_t{binary_deps=BinaryDeps}, BinaryDep) ->
-    State#state_t{binary_deps=[BinaryDep | BinaryDeps]}.
+pkg_deps(State=#state_t{pkg_deps=PkgDeps}, NewPkgDeps) when is_list(PkgDeps) ->
+    State#state_t{pkg_deps=NewPkgDeps};
+pkg_deps(State=#state_t{pkg_deps=PkgDeps}, PkgDep) ->
+    State#state_t{pkg_deps=[PkgDep | PkgDeps]}.
 
 src_deps(#state_t{src_deps=SrcDeps}) ->
     SrcDeps.
@@ -137,7 +118,19 @@ src_deps(#state_t{src_deps=SrcDeps}) ->
 src_deps(State=#state_t{src_deps=SrcDeps}, NewSrcDeps) when is_list(SrcDeps) ->
     State#state_t{src_deps=NewSrcDeps};
 src_deps(State=#state_t{src_deps=SrcDeps}, SrcDep) ->
-    State#state_t{src_deps=[SrcDep | SrcDeps]}.
+    Name = rebar_app_info:name(SrcDep),
+    NewSrcDeps = lists:keystore(Name, 2, SrcDeps, SrcDep),
+    State#state_t{src_deps=NewSrcDeps}.
+
+src_apps(#state_t{src_apps=SrcApps}) ->
+    SrcApps.
+
+src_apps(State=#state_t{src_apps=_SrcApps}, NewSrcApps) when is_list(NewSrcApps) ->
+    State#state_t{src_apps=NewSrcApps};
+src_apps(State=#state_t{src_apps=SrcApps}, NewSrcApp) ->
+    Name = rebar_app_info:name(NewSrcApp),
+    NewSrcApps = lists:keystore(Name, 2, SrcApps, NewSrcApp),
+    State#state_t{src_apps=NewSrcApps}.
 
 project_apps(#state_t{project_apps=Apps}) ->
     Apps.
@@ -153,32 +146,44 @@ providers(#state_t{providers=Providers}) ->
 providers(State, NewProviders) ->
     State#state_t{providers=NewProviders}.
 
+-spec add_provider(t(), providers:t()) -> t().
 add_provider(State=#state_t{providers=Providers}, Provider) ->
     State#state_t{providers=[Provider | Providers]}.
 
 create_logic_providers(ProviderModules, State0) ->
     lists:foldl(fun(ProviderMod, Acc) ->
-                        {ok, State1} = rebar_provider:new(ProviderMod, Acc),
-                        State1
+                        case providers:new(ProviderMod, Acc) of
+                            {error, Reason} ->
+                                ?ERROR(Reason++"~n", []),
+                                Acc;
+                            {ok, State1} ->
+                                State1
+                        end
                 end, State0, ProviderModules).
 
-prepend_hook(State=#state_t{hooks=Hooks}, Target, Hook) ->
-    {PreHooks, PostHooks} = proplists:get_value(Target, Hooks, {[], []}),
-    State#state_t{hooks=[{Target, {[Hook | PreHooks], PostHooks}} | proplists:delete(Target, Hooks)]}.
+prepend_hook(State=#state_t{providers=Providers}, Target, Hook) ->
+    State#state_t{providers=add_hook(pre, Providers, Target, Hook)}.
 
-append_hook(State=#state_t{hooks=Hooks}, Target, Hook) ->
-    {PreHooks, PostHooks} = proplists:get_value(Target, Hooks, {[], []}),
-    State#state_t{hooks=[{Target, {PreHooks, [Hook | PostHooks]}} | proplists:delete(Target, Hooks)]}.
+append_hook(State=#state_t{providers=Providers}, Target, Hook) ->
+    State#state_t{providers=add_hook(post, Providers, Target, Hook)}.
 
-hooks(#state_t{hooks=Hooks}, Target) ->
-    proplists:get_value(Target, Hooks, {[], []}).
+-spec hooks(t(), atom()) -> {[providers:t()], [providers:t()]}.
+hooks(_State=#state_t{providers=Providers}, Target) ->
+    Provider = providers:get_provider(Target, Providers),
+    providers:hooks(Provider).
 
 %% ===================================================================
 %% Internal functions
 %% ===================================================================
 
-new_globals() -> dict:new().
-
-new_env() -> dict:new().
-
-new_skip_dirs() -> dict:new().
+add_hook(Which, Providers, Target, Hook) ->
+    Provider = providers:get_provider(Target, Providers),
+    Hooks = providers:hooks(Provider),
+    NewHooks = add_hook(Which, Hooks, Hook),
+    NewProvider = providers:hooks(Provider, NewHooks),
+    [NewProvider | lists:delete(Provider, Providers)].
+
+add_hook(pre, {PreHooks, PostHooks}, Hook) ->
+    {[Hook | PreHooks], PostHooks};
+add_hook(post, {PreHooks, PostHooks}, Hook) ->
+    {PreHooks, [Hook | PostHooks]}.
diff --git a/src/rebar_templater.erl b/src/rebar_templater.erl
index a795b66..b30c517 100644
--- a/src/rebar_templater.erl
+++ b/src/rebar_templater.erl
@@ -47,6 +47,8 @@ new(app, DirName, State) ->
     create1(State, DirName, "otp_app");
 new(lib, DirName, State) ->
     create1(State, DirName, "otp_lib");
+new(plugin, DirName, State) ->
+    create1(State, DirName, "plugin");
 new(rel, DirName, State) ->
     create1(State, DirName, "otp_rel").
 
@@ -78,7 +80,7 @@ create(State) ->
 resolve_variables([], Dict) ->
     Dict;
 resolve_variables([{Key, Value0} | Rest], Dict) when is_list(Value0) ->
-    Value = render(list_to_binary(Value0), Dict),
+    Value = render(Value0, Dict),
     resolve_variables(Rest, dict:store(Key, Value, Dict));
 resolve_variables([{Key, {list, Dicts}} | Rest], Dict) when is_list(Dicts) ->
     %% just un-tag it so erlydtl can use it
@@ -376,7 +378,7 @@ execute_template(Files, [{'case', Variable, Values, Instructions} | Rest], Templ
                      ExistingFiles);
 execute_template(Files, [{template, Input, Output} | Rest], TemplateType,
                  TemplateName, Context, Force, ExistingFiles) ->
-    InputName = filename:join(filename:dirname(TemplateName), Input),
+    _InputName = filename:join(filename:dirname(TemplateName), Input),
     %File = load_file(Files, TemplateType, InputName),
     OutputTemplateName = make_template_name("rebar_output_template", Output),
     {ok, OutputTemplateName1} = erlydtl:compile_template(Output, OutputTemplateName, ?ERLYDTL_COMPILE_OPTS),
diff --git a/src/rebar_topo.erl b/src/rebar_topo.erl
index 87ee234..de3351a 100644
--- a/src/rebar_topo.erl
+++ b/src/rebar_topo.erl
@@ -54,20 +54,18 @@
 %% applications. This implies that you have already done the
 %% constraint solve before you pass the list of apps here to be
 %% sorted.
--spec sort_apps([rebar_app_info:t()]) ->
-                       {ok, [rebar_app_info:t()]} |
-                       relx:error().
+-spec sort_apps([rebar_app_info:t()]) -> {ok, [rebar_app_info:t()]} | {error, any()}.
 sort_apps(Apps) ->
     Pairs = apps_to_pairs(Apps),
     case sort(Pairs) of
         {ok, Names} ->
             {ok, names_to_apps(Names, Apps)};
         E ->
-            E
+            {error, E}
     end.
 
 %% @doc Do a topological sort on the list of pairs.
--spec sort([pair()]) -> {ok, [atom()]} | relx:error().
+-spec sort([pair()]) -> {ok, [atom()]} | {error, any()}.
 sort(Pairs) ->
     iterate(Pairs, [], all(Pairs)).
 
@@ -78,9 +76,9 @@ format_error({cycle, Pairs}) ->
      "before we can continue:\n",
     case Pairs of
         [{P1, P2}] ->
-            [rebar_util:indent(2), erlang:atom_to_list(P2), "->", erlang:atom_to_list(P1)];
+            [rebar_utils:indent(2), erlang:atom_to_list(P2), "->", erlang:atom_to_list(P1)];
         [{P1, P2} | Rest] ->
-            [rebar_util:indent(2), erlang:atom_to_list(P2), "->", erlang:atom_to_list(P1),
+            [rebar_utils:indent(2), erlang:atom_to_list(P2), "->", erlang:atom_to_list(P1),
              [["-> ", erlang:atom_to_list(PP2), " -> ", erlang:atom_to_list(PP1)] || {PP1, PP2} <- Rest]];
         [] ->
             []
@@ -91,12 +89,12 @@ format_error({cycle, Pairs}) ->
 %%====================================================================
 -spec names_to_apps([atom()], [rebar_app_info:t()]) -> [rebar_app_info:t()].
 names_to_apps(Names, Apps) ->
- [element(2, App) || App <- [find_app_by_name(Name, Apps) || Name <- Names], App =/= error].
+    [element(2, App) || App <- [find_app_by_name(Name, Apps) || Name <- Names], App =/= error].
 
 -spec find_app_by_name(atom(), [rebar_app_info:t()]) -> {ok, rebar_app_info:t()} | error.
 find_app_by_name(Name, Apps) ->
     ec_lists:find(fun(App) ->
-                          rebar_app_info:name(App) =:= Name
+                          ec_cnv:to_atom(rebar_app_info:name(App)) =:= ec_cnv:to_atom(Name)
                   end, Apps).
 
 -spec apps_to_pairs([rebar_app_info:t()]) -> [pair()].
@@ -105,20 +103,20 @@ apps_to_pairs(Apps) ->
 
 -spec app_to_pairs(rebar_app_info:t()) -> [pair()].
 app_to_pairs(App) ->
-    [{DepApp, rebar_app_info:name(App)} ||
+    [{ec_cnv:to_atom(DepApp), ec_cnv:to_atom(rebar_app_info:name(App))} ||
         DepApp <-
             rebar_app_info:deps(App)].
 
 
 %% @doc Iterate over the system.  @private
 -spec iterate([pair()], [name()], [name()]) ->
-    {ok, [name()]} | relx:error().
+    {ok, [name()]} | {error, iolist()}.
 iterate([], L, All) ->
     {ok, remove_duplicates(L ++ subtract(All, L))};
 iterate(Pairs, L, All) ->
     case subtract(lhs(Pairs), rhs(Pairs)) of
         []  ->
-            ?ERROR(format_error({cycle, Pairs}), []);
+            {error, format_error({cycle, Pairs})};
         Lhs ->
             iterate(remove_pairs(Lhs, Pairs), L ++ Lhs, All)
     end.
@@ -188,29 +186,27 @@ topo_2_test() ->
 
 topo_pairs_cycle_test() ->
     Pairs = [{app2, app1}, {app1, app2}, {stdlib, app1}],
-    ?assertMatch({error, {_, {cycle, [{app2, app1}, {app1, app2}]}}},
-                 sort(Pairs)).
+    ?assertMatch({error, _}, sort(Pairs)).
 
 topo_apps_cycle_test() ->
-    {ok, App1} = rebar_app_info:new(app1, "0.1", "/no-dir", [app2], [stdlib]),
-    {ok, App2} = rebar_app_info:new(app2, "0.1", "/no-dir", [app1], []),
+    {ok, App1} = rebar_app_info:new(app1, "0.1", "/no-dir", [app2]),
+    {ok, App2} = rebar_app_info:new(app2, "0.1", "/no-dir", [app1]),
     Apps = [App1, App2],
-    ?assertMatch({error, {_, {cycle, [{app2,app1},{app1,app2}]}}},
-                 sort_apps(Apps)).
+    ?assertMatch({error, _}, sort_apps(Apps)).
 
 topo_apps_good_test() ->
     Apps = [App ||
                {ok, App} <-
-                   [rebar_app_info:new(app1, "0.1", "/no-dir", [app2, zapp1], [stdlib, kernel]),
-                    rebar_app_info:new(app2, "0.1", "/no-dir", [app3], []),
-                    rebar_app_info:new(app3, "0.1", "/no-dir", [kernel], []),
-                    rebar_app_info:new(zapp1, "0.1", "/no-dir", [app2,app3,zapp2], []),
-                    rebar_app_info:new(stdlib, "0.1", "/no-dir", [], []),
-                    rebar_app_info:new(kernel, "0.1", "/no-dir", [], []),
-                    rebar_app_info:new(zapp2, "0.1", "/no-dir", [], [])]],
+                   [rebar_app_info:new(app1, "0.1", "/no-dir", [app2, zapp1]),
+                    rebar_app_info:new(app2, "0.1", "/no-dir", [app3]),
+                    rebar_app_info:new(app3, "0.1", "/no-dir", [kernel]),
+                    rebar_app_info:new(zapp1, "0.1", "/no-dir", [app2,app3,zapp2]),
+                    rebar_app_info:new(stdlib, "0.1", "/no-dir", []),
+                    rebar_app_info:new(kernel, "0.1", "/no-dir", []),
+                    rebar_app_info:new(zapp2, "0.1", "/no-dir", [])]],
     {ok, Sorted} = sort_apps(Apps),
     ?assertMatch([stdlib, kernel, zapp2,
                   app3, app2, zapp1, app1],
-                 [rebar_app_info:name(App) || App <- Sorted]).
+                 [ec_cnv:to_atom(rebar_app_info:name(App)) || App <- Sorted]).
 
 -endif.
diff --git a/src/rebar_utils.erl b/src/rebar_utils.erl
index b83c03e..87387be 100644
--- a/src/rebar_utils.erl
+++ b/src/rebar_utils.erl
@@ -30,42 +30,27 @@
          filtermap/2,
          get_cwd/0,
          is_arch/1,
-         get_arch/0,
-         wordsize/0,
          sh/2,
          sh_send/3,
+         abort/0,
+         abort/2,
+         escript_foldl/3,
          find_files/2,
          find_files/3,
-         now_str/0,
          ensure_dir/1,
          beam_to_mod/1,
          beams/1,
-         erl_to_mod/1,
-         abort/0,
-         abort/2,
-         escript_foldl/3,
          find_executable/1,
-         prop_check/3,
          expand_code_path/0,
-         expand_env_variable/3,
          vcs_vsn/3,
          deprecated/3,
          deprecated/4,
-         get_deprecated_global/4,
-         get_deprecated_global/5,
-         get_experimental_global/3,
-         get_experimental_local/3,
-         get_deprecated_list/4,
-         get_deprecated_list/5,
-         get_deprecated_local/4,
-         get_deprecated_local/5,
          delayed_halt/1,
          erl_opts/1,
          src_dirs/1,
          ebin_dir/0,
          processing_base_dir/1,
          processing_base_dir/2,
-         patch_env/2,
          indent/1]).
 
 %% for internal use only
@@ -177,11 +162,6 @@ find_files(Dir, Regex, Recursive) ->
     filelib:fold_files(Dir, Regex, Recursive,
                        fun(F, Acc) -> [F | Acc] end, []).
 
-now_str() ->
-    {{Year, Month, Day}, {Hour, Minute, Second}} = calendar:local_time(),
-    lists:flatten(io_lib:format("~4b/~2..0b/~2..0b ~2..0b:~2..0b:~2..0b",
-                                [Year, Month, Day, Hour, Minute, Second])).
-
 %% TODO: filelib:ensure_dir/1 corrected in R13B04. Remove when we drop
 %% support for OTP releases older than R13B04.
 ensure_dir(Path) ->
@@ -194,27 +174,6 @@ ensure_dir(Path) ->
             Error
     end.
 
--spec abort() -> no_return().
-abort() ->
-    throw(rebar_abort).
-
--spec abort(string(), [term()]) -> no_return().
-abort(String, Args) ->
-    ?ERROR(String, Args),
-    abort().
-
-%% TODO: Rename emulate_escript_foldl to escript_foldl and remove
-%% this function when the time is right. escript:foldl/3 was an
-%% undocumented exported fun and has been removed in R14.
-escript_foldl(Fun, Acc, File) ->
-    {module, zip} = code:ensure_loaded(zip),
-    case erlang:function_exported(zip, foldl, 3) of
-        true ->
-            emulate_escript_foldl(Fun, Acc, File);
-        false ->
-            escript:foldl(Fun, Acc, File)
-    end.
-
 find_executable(Name) ->
     case os:find_executable(Name) of
         false -> false;
@@ -222,10 +181,6 @@ find_executable(Name) ->
             "\"" ++ filename:nativename(Path) ++ "\""
     end.
 
-%% Helper function for checking values and aborting when needed
-prop_check(true, _, _) -> true;
-prop_check(false, Msg, Args) -> ?ABORT(Msg, Args).
-
 %% Convert all the entries in the code path to absolute paths.
 expand_code_path() ->
     CodePath = lists:foldl(fun(Path, Acc) ->
@@ -233,25 +188,6 @@ expand_code_path() ->
                            end, [], code:get_path()),
     code:set_path(lists:reverse(CodePath)).
 
-%%
-%% Given env. variable FOO we want to expand all references to
-%% it in InStr. References can have two forms: $FOO and ${FOO}
-%% The end of form $FOO is delimited with whitespace or eol
-%%
-expand_env_variable(InStr, VarName, RawVarValue) ->
-    case string:chr(InStr, $$) of
-        0 ->
-            %% No variables to expand
-            InStr;
-        _ ->
-            ReOpts = [global, unicode, {return, list}],
-            VarValue = re:replace(RawVarValue, "\\\\", "\\\\\\\\", ReOpts),
-            %% Use a regex to match/replace:
-            %% Given variable "FOO": match $FOO\s | $FOOeol | ${FOO}
-            RegEx = io_lib:format("\\\$(~s(\\s|$)|{~s})", [VarName, VarName]),
-            re:replace(InStr, RegEx, [VarValue, "\\2"], ReOpts)
-    end.
-
 vcs_vsn(Config, Vsn, Dir) ->
     Key = {Vsn, Dir},
     Cache = rebar_state:get(Config, vsn_cache, dict:new()),
@@ -265,33 +201,6 @@ vcs_vsn(Config, Vsn, Dir) ->
             {Config, VsnString}
     end.
 
-get_deprecated_global(Config, OldOpt, NewOpt, When) ->
-    get_deprecated_global(Config, OldOpt, NewOpt, undefined, When).
-
-get_deprecated_global(Config, OldOpt, NewOpt, Default, When) ->
-    get_deprecated_3(fun rebar_state:get/3,
-                     Config, OldOpt, NewOpt, Default, When).
-
-get_experimental_global(Config, Opt, Default) ->
-    get_experimental_3(fun rebar_state:get/3, Config, Opt, Default).
-
-get_experimental_local(Config, Opt, Default) ->
-    get_experimental_3(fun rebar_state:get/3, Config, Opt, Default).
-
-get_deprecated_list(Config, OldOpt, NewOpt, When) ->
-    get_deprecated_list(Config, OldOpt, NewOpt, undefined, When).
-
-get_deprecated_list(Config, OldOpt, NewOpt, Default, When) ->
-    get_deprecated_3(fun rebar_state:get_list/3,
-                     Config, OldOpt, NewOpt, Default, When).
-
-get_deprecated_local(Config, OldOpt, NewOpt, When) ->
-    get_deprecated_local(Config, OldOpt, NewOpt, undefined, When).
-
-get_deprecated_local(Config, OldOpt, NewOpt, Default, When) ->
-    get_deprecated_3(fun rebar_state:get/3,
-                     Config, OldOpt, NewOpt, Default, When).
-
 deprecated(Old, New, Opts, When) when is_list(Opts) ->
     case lists:member(Old, Opts) of
         true ->
@@ -337,7 +246,7 @@ delayed_halt(Code) ->
     end.
 
 %% @doc Return list of erl_opts
--spec erl_opts(rebar_state:config()) -> list().
+-spec erl_opts(rebar_state:t()) -> list().
 erl_opts(Config) ->
     RawErlOpts = filter_defines(rebar_state:get(Config, erl_opts, []), []),
     Defines = [{d, list_to_atom(D)} ||
@@ -367,25 +276,6 @@ processing_base_dir(State, Dir) ->
     AbsDir = filename:absname(Dir),
     AbsDir =:= rebar_state:get(State, base_dir).
 
-%% @doc Returns the list of environment variables including 'REBAR' which
-%% points to the rebar executable used to execute the currently running
-%% command. The environment is not modified if rebar was invoked
-%% programmatically.
--spec patch_env(rebar_state:config(), [{string(), string()}])
-               -> [{string(), string()}].
-patch_env(Config, []) ->
-    %% If we reached an empty list, the env did not contain the REBAR variable.
-    case rebar_state:get(Config, escript, "") of
-        "" -> % rebar was invoked programmatically
-            [];
-        Path ->
-            [{"REBAR", Path}]
-    end;
-patch_env(_Config, [{"REBAR", _} | _]=All) ->
-    All;
-patch_env(Config, [E | Rest]) ->
-    [E | patch_env(Config, Rest)].
-
 %% ====================================================================
 %% Internal functions
 %% ====================================================================
@@ -426,30 +316,6 @@ otp_release1(Rel) ->
             binary:bin_to_list(Vsn, {0, Size - 1})
     end.
 
-get_deprecated_3(Get, Config, OldOpt, NewOpt, Default, When) ->
-    case Get(Config, NewOpt, Default) of
-        Default ->
-            case Get(Config, OldOpt, Default) of
-                Default ->
-                    Default;
-                Old ->
-                    deprecated(OldOpt, NewOpt, When),
-                    Old
-            end;
-        New ->
-            New
-    end.
-
-get_experimental_3(Get, Config, Opt, Default) ->
-    Val = Get(Config, Opt, Default),
-    case Val of
-        Default ->
-            Default;
-        Val ->
-            ?CONSOLE("NOTICE: Using experimental option '~p'~n", [Opt]),
-            Val
-    end.
-
 %% We do the shell variable substitution ourselves on Windows and hope that the
 %% command doesn't use any other shell magic.
 patch_on_windows(Cmd, Env) ->
@@ -466,6 +332,25 @@ patch_on_windows(Cmd, Env) ->
             Cmd
     end.
 
+%%
+%% Given env. variable FOO we want to expand all references to
+%% it in InStr. References can have two forms: $FOO and ${FOO}
+%% The end of form $FOO is delimited with whitespace or eol
+%%
+expand_env_variable(InStr, VarName, RawVarValue) ->
+    case string:chr(InStr, $$) of
+        0 ->
+            %% No variables to expand
+            InStr;
+        _ ->
+            ReOpts = [global, unicode, {return, list}],
+            VarValue = re:replace(RawVarValue, "\\\\", "\\\\\\\\", ReOpts),
+            %% Use a regex to match/replace:
+            %% Given variable "FOO": match $FOO\s | $FOOeol | ${FOO}
+            RegEx = io_lib:format("\\\$(~s(\\s|$)|{~s})", [VarName, VarName]),
+            re:replace(InStr, RegEx, [VarValue, "\\2"], ReOpts)
+    end.
+
 expand_sh_flag(return_on_error) ->
     {error_handler,
      fun(_Command, Err) ->
@@ -521,14 +406,19 @@ sh_loop(Port, Fun, Acc) ->
 beam_to_mod(Filename) ->
     list_to_atom(filename:basename(Filename, ".beam")).
 
-erl_to_mod(Filename) ->
-    list_to_atom(filename:rootname(filename:basename(Filename))).
-
 beams(Dir) ->
     filelib:fold_files(Dir, ".*\.beam\$", true,
                        fun(F, Acc) -> [F | Acc] end, []).
 
-emulate_escript_foldl(Fun, Acc, File) ->
+-spec abort() -> no_return().
+abort() ->
+    throw(rebar_abort).
+-spec abort(string(), [term()]) -> no_return().
+abort(String, Args) ->
+    ?ERROR(String, Args),
+    abort().
+
+escript_foldl(Fun, Acc, File) ->
     case escript:extract(File, [compile_source]) of
         {ok, [_Shebang, _Comment, _EmuArgs, Body]} ->
             case Body of