Added rec and mdo keyword to grammar

Added automatic indent after `mdo`

Fixes #29

src/extension.ts

@@ -8,7 +8,7 @@ export function activate(context: vscode.ExtensionContext) {
 
         indentationRules: {
             // ^.*\{[^}"']*$
-            increaseIndentPattern: /((\b(if\b.*|then|else|do|of|let|in|where))|=|->|>>=|>=>|=<<|(^(data)( |\t)+(\w|')+( |\t)*))( |\t)*$/,
+            increaseIndentPattern: /((\b(if\b.*|then|else|m?do|of|let|in|where))|=|->|>>=|>=>|=<<|(^(data)( |\t)+(\w|')+( |\t)*))( |\t)*$/,
             decreaseIndentPattern: null
         },
         wordPattern: /([\w'_][\w'_\d]*)|([0-9]+\.[0-9]+([eE][+-]?[0-9]+)?|[0-9]+[eE][+-]?[0-9]+)/

syntaxes/haskell.tmLanguage

@@ -316,11 +316,10 @@
 			( deriving
 			| where
 			| type([\t ]+(family|role))
-			| case
-			| of
 			| let
 			| in
 			| default
+			| rec
 			)(\b(?!'))
 			</string>
 			<key>name</key>
@@ -334,7 +333,7 @@
 		</dict>
 		<dict>
 			<key>match</key>
-			<string>\b(do|if|then|else)(\b(?!'))</string>
+			<string>\b(m?do|if|then|else|case|of)(\b(?!'))</string>
 			<key>name</key>
 			<string>keyword.control.haskell</string>
 		</dict>

test.hs

@@ -1,5 +1,6 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE RecursiveDo #-}
 module Main where
 
 import Data.Version as V (Version(..))
@@ -36,6 +37,14 @@ someFunc = do
     ident' = 9
 
 
+recDo = mdo
+    a <- b
+    return b
+
+explicitRecDo = do
+    a <- rec { c <- d }
+    return a
+
 anotherFunc :: MyData -> Int
 anotherFunc arg = 
     let something = "hello" :: String in expression