15 Aug
2016
15 Aug
'16
9:04 a.m.
Michael Orlitzky
On 08/14/2016 06:54 PM, David Feuer wrote:
Since decimal notation is defined in terms of fromRational, it seems a bit strange that the notation doesn't work for read::String->Rational. I'd be in favor of allowing it. I wouldn't expect too severe a performance penalty.
One potential gotcha:
ghci> read (show (1/3)) == (1/3) True ghci> read (show (1/3 :: Float)) == (1/3) False
When does it work? Is it platform-dependent?
Well, you are showing 1/3 as a Float and reading it as a Double, which of course won't work since the String represents a Float and not a Double. The following does work: λ: read (show (1/3 :: Float)) == ((1/3) :: Float) True