Add showcase for module layouting

[ci skip]

doc/showcases/Module.md

@@ -0,0 +1,89 @@
+
+Last updated for brittany version `0.10.0.0`.
+
+# Example layouting of the module header (exports/imports)
+
+## On default settings
+
+~~~~.hs
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE LambdaCase #-}
+
+module Main
+  ( main
+  )
+where
+
+import qualified Paths_brittany
+import           Language.Haskell.Brittany
+
+import           Network.Wai
+import           Network.HTTP.Types
+import qualified Network.Wai.Handler.Warp      as Warp
+
+import           Data.String
+
+import qualified Data.ByteString               as BS
+import qualified Data.ByteString.Lazy          as BSL
+
+import           Control.Monad.Loops
+
+import qualified Data.Text.Encoding            as Text
+import qualified Data.Text                     as Text
+
+import           Data.Version                   ( showVersion )
+
+import qualified System.Mem
+import qualified Control.Concurrent
+import           Control.Concurrent.Async       ( async
+                                                , waitEitherCatch
+                                                , waitEitherCatchCancel
+                                                )
+import qualified Data.Aeson                    as Aeson
+import           Data.Time.Clock
+import           Data.Time.Format
+import           Text.Parsec             hiding ( (<|>) )
+~~~~
+
+For long module names, things will be moved one line below and aligned as
+before. Long identifiers may overflow our 80 column limit:
+
+~~~~.hs
+import qualified Example.Very.Long.Module.Name.Internal
+                                               as T
+import           Example.Very.Long.Module.Name.Internal
+                                                ( a
+                                                , b
+                                                , c
+                                                )
+import           Example.Very.Long.Module.Name.Internal
+                                                ( someVeryLongAndDescriptiveFunctionName
+                                                )
+~~~~
+
+## Alternative setting
+
+If you have many long module names or use large identifiers, you might
+be interested in these alternative settings:
+
+~~~~
+conf_layout:
+  lconfig_importColumn: 21
+  lconfig_importAsColumn: 70
+~~~~
+
+Now, our previous examples becomes:
+
+~~~~.hs
+import qualified Example.Very.Long.Module.Name.Strict.Internal     as T
+import           Example.Very.Long.Module.Name.Strict.Internal
+                   ( a
+                   , b
+                   , c
+                   )
+import           Example.Very.Long.Module.Name.Strict.Internal
+                   ( someVeryLongAndDescriptiveFunctionName
+                   )
+~~~~