Report cli errors on run

This is mostly helpful when debugging or writing programs, not during usage, but
I shouldn't be suppressing errors anyway.

My first version of this patch used `Biz.Log` instead of `panic`. Unfortunately
this exposed a bug in bild: Control/Concurrent/Go.hs (and others) failed to
build because it imported `Biz.Cli` which imported `Biz.Log`, and bild couldn't
find `Biz/Log.hs`. So apparently my function `detectHaskellImports` doesn't
detect all Haskell imports, somewhere along the lines I cut the graph short
instead of recursing. I guess that will be a project for another day.

1 files changed, 12 insertions, 8 deletions

diff --git a/Biz/Cli.hs b/Biz/Cli.hs
index b3c7583..5029792 100644
--- a/Biz/Cli.hs
+++ b/Biz/Cli.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE NoImplicitPrelude #-}
 
@@ -33,14 +35,16 @@ data Plan cfg = Plan
 main :: Plan cfg -> IO ()
 main Plan {..} =
   Environment.getArgs
-    +> Docopt.parseArgsOrExit help
-    +> \args ->
-      if args `has` Docopt.command "test"
-        then Test.run test
-        else
-          if args `has` Docopt.longOption "help" || args `has` Docopt.shortOption 'h'
-            then Docopt.exitWithUsage help
-            else move args
+    /> Docopt.parseArgs help
+    +> \case
+      Left err -> panic <| show err
+      Right args ->
+        if args `has` Docopt.command "test"
+          then Test.run test
+          else
+            if args `has` Docopt.longOption "help" || args `has` Docopt.shortOption 'h'
+              then Docopt.exitWithUsage help
+              else move args
 
 has :: Docopt.Arguments -> Docopt.Option -> Bool
 has = Docopt.isPresent