Add new format command

Author: robinheghan

src/Main.gren

@@ -16,6 +16,7 @@ import Terminal.Run
 import Terminal.Help
 import Terminal.Repl
 import Terminal.Report exposing (Report)
+import Terminal.Format
 import Compiler.Backend
 import Compiler.PackageName as PackageName exposing (PackageName)
 import Compiler.Paths
@@ -839,6 +840,13 @@ parseUserArgs model compilerPath =
                         |> Task.onError endWithErrorString
                         |> Task.perform RunCmd
 
+                CliParser.Format ->
+                    Terminal.Format.run
+                        { stdout = model.stdout
+                        }
+                        |> Task.map (\_ -> Cmd.none)
+                        |> Task.perform RunCmd
+
 
 resolveProject : Model -> Task Report Terminal.PackageInstall.PackageResolution
 resolveProject model =

src/Terminal/Format.gren

@@ -0,0 +1,20 @@
+module Terminal.Format exposing
+    ( Config
+    , run
+    )
+
+
+import Stream
+import Stream.Log
+import Task exposing (Task)
+import Bytes exposing (Bytes)
+
+
+type alias Config =
+    { stdout : Stream.Writable Bytes
+    }
+
+
+run : Config -> Task x {}
+run config =
+    Stream.Log.line config.stdout "TODO"

src/Terminal/Parser.gren

@@ -31,6 +31,7 @@ type Command
     | PackageDiff DiffArgs
     | Paths Paths.Options
     | Run RunOptions
+    | Format
 
 
 type alias InitFlags =
@@ -203,6 +204,20 @@ parser =
                 , builder =
                     \_args flags -> Paths flags
                 }
+            |> CLI.Parser.withCommand
+                { word = "format"
+                , arguments =
+                    CLI.Parser.noArgs
+                , flags =
+                    CLI.Parser.noFlags
+                , commonDescription = Nothing
+                , summary =
+                    "Format Gren source code."
+                , example =
+                    PP.empty
+                , builder =
+                    \_args _flags -> Format
+                }
             |> CLI.Parser.withCommand
                 { word = "make"
                 , arguments =