Fix indentation for multiline Some-, toMap- and merge-expressions (#1377)

The loss of indentation for toMap and merge was due to
75e6cc5ca7. I have included Some for
consistency.

Fixes #1376.

Also improve format test failure messages

dhall/src/Dhall/Pretty/Internal.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP               #-}
+{-# LANGUAGE LambdaCase        #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards   #-}
 
@@ -837,22 +838,20 @@ prettyCharacterSet characterSet expression =
         prettyApplicationExpression a0
 
     prettyApplicationExpression :: Pretty a => Expr Src a -> Doc Ann
-    prettyApplicationExpression a0 = case a0 of
+    prettyApplicationExpression = \case
-        App   {} -> result
+        App a b           -> f (prettyApplicationExpression a) [b]
-        Some  {} -> result
+        Some a            -> f (builtin "Some") [a]
-        ToMap {} -> result
+        ToMap a Nothing   -> f (keyword "toMap") [a]
-        Merge {} -> result
+        Merge a b Nothing -> f (keyword "merge") [a, b]
-        Note _ b -> prettyApplicationExpression b
+        Note _ b          -> prettyApplicationExpression b
-        _        -> prettyImportExpression a0
+        e                 -> prettyImportExpression e
       where
-        result = enclose' "" "" " " "" (reverse (docs a0))
+        f a bs =
-
+            enclose'
-        docs (App  a b) = ( prettyImportExpression b, Pretty.indent 2 (prettyImportExpression b) ) : docs a
+                "" "" " " ""
-        docs (Some   a) = map duplicate [ prettyImportExpression a , builtin "Some" ]
+                ( duplicate a
-        docs (ToMap a Nothing) = map duplicate [ prettyImportExpression a, keyword "toMap" ]
+                : map (fmap (Pretty.indent 2) . duplicate . prettyImportExpression) bs
-        docs (Merge a b Nothing) = map duplicate [ prettyImportExpression b, prettyImportExpression a, keyword "merge" ]
+                )
-        docs (Note _ b) = docs b
-        docs         b  = map duplicate [ prettyImportExpression b ]
 
     prettyImportExpression :: Pretty a => Expr Src a -> Doc Ann
     prettyImportExpression (Embed a) =

dhall/tests/Dhall/Test/Format.hs

@@ -61,6 +61,10 @@ formatTest characterSet prefix =
         expectedText <- Text.IO.readFile outputFile
 
         let message =
-                "The formatted expression did not match the expected output"
+                   "The formatted expression did not match the expected output\n"
+                <> "Expected:\n\n" <> Text.unpack expectedText <> "\n\n"
+                <> "Actual:\n\n" <> Text.unpack actualText <> "\n\n"
+                <> "Expected (show): " <> show expectedText <> "\n"
+                <> "Actual   (show): " <> show actualText <> "\n"
 
-        Tasty.HUnit.assertEqual message expectedText actualText
+        Tasty.HUnit.assertBool message (actualText == expectedText)

dhall/tests/format/applicationMultilineA.dhall

@@ -0,0 +1,5 @@
+{ app = ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff aaaaaaaaaaaaaaaaa
+, some = Some aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+, merge = merge aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+, toMap = toMap aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+}

dhall/tests/format/applicationMultilineB.dhall

@@ -0,0 +1,14 @@
+{ app =
+    ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+      aaaaaaaaaaaaaaaaa
+, some =
+    Some
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+, merge =
+    merge
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+      bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+, toMap =
+    toMap
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+}

dhall/tests/format/largeRecordB.dhall

@@ -34,15 +34,15 @@ in    defaults.Config
       , dark_room = Some False
       , disclose =
           Some
-          (   defaults.Disclose
+            (   defaults.Disclose
-            ⫽ { inventory = Some { prompt = True, default = True }
+              ⫽ { inventory = Some { prompt = True, default = True }
-              , attributes = Some { prompt = True, default = False }
+                , attributes = Some { prompt = True, default = False }
-              , monsters_killed = Some { prompt = False, default = True }
+                , monsters_killed = Some { prompt = False, default = True }
-              , monsters_genocided = Some { prompt = False, default = False }
+                , monsters_genocided = Some { prompt = False, default = False }
-              , conduct = Some { prompt = False, default = False }
+                , conduct = Some { prompt = False, default = False }
-              , dungeon_overview = Some { prompt = False, default = False }
+                , dungeon_overview = Some { prompt = False, default = False }
-              }
+                }
-          )
+            )
       , dogname = Some "Cujo"
       , extmenu = Some False
       , fixinv = Some True