Add a language pragma style "vertical_compact".

Author: Javran

data/stylish-haskell.yaml

@@ -300,7 +300,9 @@ steps:
       # - compact: A more compact style.
       #
       # - compact_line: Similar to compact, but wrap each line with
-      #   `{-#LANGUAGE #-}'.
+      #   `{-# LANGUAGE #-}'.
+      #
+      # - vertical_compact: Similar to vertical, but use only one language pragma.
       #
       # Default: vertical.
       style: vertical

lib/Language/Haskell/Stylish/Config.hs

@@ -336,9 +336,10 @@ parseLanguagePragmas config o = LanguagePragmas.step
     <*> mkLanguage o
   where
     styles =
-        [ ("vertical",     LanguagePragmas.Vertical)
-        , ("compact",      LanguagePragmas.Compact)
-        , ("compact_line", LanguagePragmas.CompactLine)
+        [ ("vertical",         LanguagePragmas.Vertical)
+        , ("compact",          LanguagePragmas.Compact)
+        , ("compact_line",     LanguagePragmas.CompactLine)
+        , ("vertical_compact", LanguagePragmas.VerticalCompact)
         ]
 
 

lib/Language/Haskell/Stylish/Step/LanguagePragmas.hs

@@ -37,6 +37,7 @@ data Style
     = Vertical
     | Compact
     | CompactLine
+    | VerticalCompact
     deriving (Eq, Show)
 
 
@@ -73,6 +74,16 @@ compactLinePragmas lg columns align pragmas' = map (wrapLanguage . pad) prags
       map (++ ",") (init pragmas') ++ [last pragmas']
 
 
+--------------------------------------------------------------------------------
+verticalCompactPragmas :: String -> [String] -> Lines
+verticalCompactPragmas lg pragmas' =
+  [ "{-# " <> lg
+  , "    " <> head pragmas'
+  ]
+  <> [ "  , "  <> pragma | pragma <- tail pragmas']
+  <> [ "  #-}"]
+
+
 --------------------------------------------------------------------------------
 truncateComma :: String -> String
 truncateComma ""     = ""
@@ -83,9 +94,10 @@ truncateComma xs
 
 --------------------------------------------------------------------------------
 prettyPragmas :: String -> Maybe Int -> Int -> Bool -> Style -> [String] -> Lines
-prettyPragmas lp _    longest align Vertical    = verticalPragmas lp longest align
-prettyPragmas lp cols _       _     Compact     = compactPragmas lp cols
-prettyPragmas lp cols _       align CompactLine = compactLinePragmas lp cols align
+prettyPragmas lp _    longest align Vertical        = verticalPragmas lp longest align
+prettyPragmas lp cols _       _     Compact         = compactPragmas lp cols
+prettyPragmas lp cols _       align CompactLine     = compactLinePragmas lp cols align
+prettyPragmas lp _    _       _     VerticalCompact = verticalCompactPragmas lp
 
 
 --------------------------------------------------------------------------------

tests/Language/Haskell/Stylish/Step/LanguagePragmas/Tests.hs

@@ -227,3 +227,25 @@ case13 = assertSnippet
         , "{-# LANGUAGE DeriveFunctor #-}"
         , "main = let !x = 1 + 1 in print x"
         ]
+
+--------------------------------------------------------------------------------
+case13 :: Assertion
+case13 = expected @=? testStep (step Nothing VerticalCompact False False "language") input
+  where
+    input = unlines
+        [ "{-# LANGUAGE ViewPatterns, OverloadedStrings #-}"
+        , "{-# LANGUAGE TemplateHaskell, ViewPatterns #-}"
+        , "{-# LANGUAGE ScopedTypeVariables, NoImplicitPrelude #-}"
+        , "module Main where"
+        ]
+
+    expected = unlines
+        [ "{-# language"
+        , "    NoImplicitPrelude"
+        , "  , OverloadedStrings"
+        , "  , ScopedTypeVariables"
+        , "  , TemplateHaskell"
+        , "  , ViewPatterns"
+        , "  #-}"
+        , "module Main where"
+        ]