#1920: Show instance for Ratio is wrong
----------------------------+-----------------------------------------------
Reporter: guest | Owner: simonmar
Type: bug | Status: new
Priority: normal | Milestone: 6.8 branch
Component: libraries/base | Version: 6.6.1
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: Unknown
Os: Unknown |
----------------------------+-----------------------------------------------
Old description:
> GHCi> :m Data.Ratio
> GHCi> show (1%2)
> "1%2"
>
> Hugs> :l Data.Ratio
> Hugs> show (1%2)
> "1 % 2"
>
> The Haskell report specifies
> (http://haskell.org/onlinereport/ratio.html):
>
> instance (Integral a) => Show (Ratio a) where
> showsPrec p (x:%y) = showParen (p > ratPrec)
> (showsPrec (ratPrec+1) x .
> showString " % " .
> showsPrec (ratPrec+1) y)
>
> This effects the nofib suite, where the expected.stdout files are based
> on GHC's incorrect Ratio implementation.
>
> Tested only on 6.6.1.
New description:
{{{
GHCi> :m Data.Ratio
GHCi> show (1%2)
"1%2"
Hugs> :l Data.Ratio
Hugs> show (1%2)
"1 % 2"
}}}
The Haskell report specifies (http://haskell.org/onlinereport/ratio.html):
{{{
instance (Integral a) => Show (Ratio a) where
showsPrec p (x:%y) = showParen (p > ratPrec)
(showsPrec (ratPrec+1) x .
showString " % " .
showsPrec (ratPrec+1) y)
}}}
This effects the nofib suite, where the expected.stdout files are based on
GHC's incorrect Ratio implementation.
Tested only on 6.6.1.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1920#comment:13>
GHC <http://www.haskell.org/ghc/>
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