#2353: GHC inliner doesn't
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Reporter: guest | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.12 branch
Component: Compiler | Version: 6.9
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
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Comment (by ross):
I think I've just tripped over this one. In Data.Foldable, there is
{{{
toList :: Foldable t => t a -> [a]
toList t = build (\ c n -> Data.Foldable.foldr c n t)
}}}
so I would expect
{{{
f :: Foldable t => t a -> [a]
f xs = last (map (:[]) (toList xs))
}}}
(only using last to simplify the example) to deforest to the equivalent of
{{{
f xs = last (Data.Foldable.foldr (\ x -> [x]:) [] xs)
}}}
but it doesn't, because toList isn't inlined until too late, even if I
give it an INLINE pragma.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2353#comment:13>
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