#2271: floor, ceiling, round :: Double -> Int are awesomely slow
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Reporter: dons | Owner: daniel.is.fischer
Type: bug | Status: patch
Priority: low | Milestone: 7.0.1
Component: libraries/base | Version: 7.1
Keywords: performance, math, double | Testcase:
Blockedby: | Difficulty: Unknown
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by daniel.is.fischer):
Either
{{{
"truncate/Float->Int8"
forall x. truncate x = (fromIntegral :: Int -> Int8) (truncateFloatInt
x)
}}}
or
{{{
"truncate/Float->Int8"
forall x. truncate x = (fromIntegral :: Int -> Int8) ((truncate ::
Float -> Int) x)
}}}
Well, I guess we could leave the type signature off truncate in the latter
and rely on type inference.
The import cycle is not created by the rules per se, but to define the
rules, we need the involved types and functions in scope. IntN and WordN
aren't in scope in GHC.Float, bringing them into scope there creates the
import cycle. So the other obvious solution is to bring Double, Float and
the functions into scope in GHC.Int and GHC.Word.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2271#comment:26>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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