Use explicit language extensions & remove extension fields from base.cabal

Add explicit {-# LANGUAGE xxx #-} pragmas to each module, that say
what extensions that module uses.  This makes it clearer where
different extensions are used in the (large, variagated) base package.

Now base.cabal doesn't need any extensions field

Thanks to Bas van Dijk for doing all the work.

1 files changed, 2 insertions, 0 deletions

diff --git a/libraries/base/Data/Traversable.hs b/libraries/base/Data/Traversable.hs
index af04e51f3a..2bdc1bc26d 100644
--- a/libraries/base/Data/Traversable.hs
+++ b/libraries/base/Data/Traversable.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Traversable