remove unused ghc extensions from compiler (#433)

removed unused ghc extension from the Encore compiler

src/back/CCode/Main.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE FlexibleInstances,FlexibleContexts,MultiParamTypeClasses,StandaloneDeriving #-}
+{-# LANGUAGE FlexibleInstances,MultiParamTypeClasses,StandaloneDeriving #-}
 
 {-| Provides the CCode data type, a representation of C
 programs that can be pretty-printed to sometimes-legal C code. The

src/back/CCode/PrettyCCode.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE GADTs,FlexibleContexts,OverloadedStrings #-}
+{-# LANGUAGE OverloadedStrings #-}
 {-# OPTIONS_GHC -fwarn-incomplete-patterns #-}
 
 {-|

src/back/CodeGen/CCodeNames.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE GADTs,FlexibleContexts #-}
+{-# LANGUAGE FlexibleContexts #-}
 {-|
 Defines how things will be called in the CCode generated by CodeGen.hs
 Provides mappings from class/method names to their C-name.

src/back/CodeGen/ClassDecl.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances, FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
 
 {-|
 

src/back/CodeGen/Closure.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances, FlexibleInstances #-}
-
 {-| Makes @Closure@ (see "AST") an instance of @Translatable@ (see "CodeGen.Typeclasses") -}
 module CodeGen.Closure (
   translateClosure,

src/back/CodeGen/Expr.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances, FlexibleInstances, GADTs, FlexibleContexts #-}
+{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
 
 {-| Makes @Expr@ an instance of @Translatable@ (see "CodeGen.Typeclasses") -}
 

src/back/CodeGen/Function.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances, FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses,  FlexibleInstances #-}
 
 {-| Makes @Function@ (see "AST") an instance of @Translatable@ (see "CodeGen.Typeclasses") -}
 module CodeGen.Function where

src/back/CodeGen/MethodDecl.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances, FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
 
 {-| Makes @MethodDecl@ (see "AST") an instance of @Translatable@ (see "CodeGen.Typeclasses") -}
 module CodeGen.MethodDecl where

src/back/CodeGen/Shared.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
-
 module CodeGen.Shared(generateShared) where
 
 import CCode.Main

src/back/CodeGen/Task.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances, FlexibleInstances #-}
-
 module CodeGen.Task where
 
 import CCode.Main

src/back/CodeGen/Trace.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE GADTs #-}
-
 module CodeGen.Trace (
   traceVariable
   , traceFuture

src/back/CodeGen/Type.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances, FlexibleInstances, GADTs #-}
+{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
 
 {-| Make Type (see "AST") an instance of @Translatable@ (see
 "CodeGen.Typeclasses"). -}

src/types/Types.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE TypeSynonymInstances #-}
-{-# LANGUAGE FlexibleInstances #-}
 {-# OPTIONS_GHC -fwarn-incomplete-patterns #-}
 module Types(
               Type