Commit 3bdc78b5 authored by Sjoerd Visscher's avatar Sjoerd Visscher
Browse files

Make DeriveTraversable imply DeriveFunctor/Foldable

Implements #9069
parent 5c89f880
......@@ -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)]
......@@ -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>.
You can also use a standalone deriving declaration instead
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