Add LANGUAGE pragmas to compiler/ source files

In some cases, the layout of the LANGUAGE/OPTIONS_GHC lines has been
reorganized, while following the convention, to

- place `{-# LANGUAGE #-}` pragmas at the top of the source file, before
  any `{-# OPTIONS_GHC #-}`-lines.

- Moreover, if the list of language extensions fit into a single
  `{-# LANGUAGE ... -#}`-line (shorter than 80 characters), keep it on one
  line. Otherwise split into `{-# LANGUAGE ... -#}`-lines for each
  individual language extension. In both cases, try to keep the
  enumeration alphabetically ordered.
  (The latter layout is preferable as it's more diff-friendly)

While at it, this also replaces obsolete `{-# OPTIONS ... #-}` pragma
occurences by `{-# OPTIONS_GHC ... #-}` pragmas.

1 files changed, 2 insertions, 0 deletions

diff --git a/compiler/deSugar/DsMonad.lhs b/compiler/deSugar/DsMonad.lhs
index b590f4b2d2..c017a7cc01 100644
--- a/compiler/deSugar/DsMonad.lhs
+++ b/compiler/deSugar/DsMonad.lhs
@@ -6,6 +6,8 @@
 @DsMonad@: monadery used in desugaring
 
 \begin{code}
+{-# LANGUAGE FlexibleInstances #-}
+
 module DsMonad (
         DsM, mapM, mapAndUnzipM,
         initDs, initDsTc, fixDs,