Commit 49ca2a37 authored by Committed by Simon Peyton JonesBrowse files
Changed deriving of Functor, Foldable, Traversable to fix #7436. Added foldMap...
Changed deriving of Functor, Foldable, Traversable to fix #7436. Added foldMap to derived Foldable instance. The derived instances will no longer eta-expand the function. I.e. instead of fmap f (Foo a) = Foo (fmap (\x -> f x) a) we now derive fmap f (Foo a) = Foo (fmap f a) Some superflous lambdas are generated as a result. For example data X a = X (a,a) fmap f (X x) = (\y -> case y of (a,b) -> (f a, f b)) x The optimizer should be able to simplify this code, as it is just beta reduction. The derived Foldable instance now includes foldMap in addition to foldr.