[commit: ghc] master: Make DeriveTraversable imply DeriveFunctor/Foldable (3bdc78b)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/3bdc78b520c05706f8b66033b154c07ed021ac33/ghc

>---------------------------------------------------------------

commit 3bdc78b520c05706f8b66033b154c07ed021ac33
Author: Sjoerd Visscher <sjoerd at w3future.com>
Date:   Fri Jun 6 15:24:41 2014 +0200

    Make DeriveTraversable imply DeriveFunctor/Foldable
    
    Implements #9069


>---------------------------------------------------------------

3bdc78b520c05706f8b66033b154c07ed021ac33
 compiler/main/DynFlags.hs         | 3 +++
 docs/users_guide/glasgow_exts.xml | 6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index 4db1d2c..5f125ef 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -2957,6 +2957,9 @@ impliedFlags
     , (Opt_ImplicitParams, turnOn, Opt_FlexibleInstances)
 
     , (Opt_JavaScriptFFI, turnOn, Opt_InterruptibleFFI)
+    
+    , (Opt_DeriveTraversable, turnOn, Opt_DeriveFunctor)
+    , (Opt_DeriveTraversable, turnOn, Opt_DeriveFoldable)
   ]
 
 optLevelFlags :: [([Int], GeneralFlag)]
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml
index d5dfa4d..ac8004f 100644
--- a/docs/users_guide/glasgow_exts.xml
+++ b/docs/users_guide/glasgow_exts.xml
@@ -3882,7 +3882,11 @@ defined in <literal>Data.Foldable</literal>.
 
 <listitem><para> With <option>-XDeriveTraversable</option>, you can derive instances of
 the class <literal>Traversable</literal>,
-defined in <literal>Data.Traversable</literal>.
+defined in <literal>Data.Traversable</literal>. Since the <literal>Traversable</literal>
+instance dictates the instances of <literal>Functor</literal> and 
+<literal>Foldable</literal>, you'll probably want to derive them too, so
+<option>-XDeriveTraversable</option> implies
+<option>-XDeriveFunctor</option> and <option>-XDeriveFoldable</option>.
 </para></listitem>
 </itemizedlist>
 You can also use a standalone deriving declaration instead