cvs commit: hugs98/libraries/Hugs Prelude.hs

[Ross Paterson]

On Tue, Oct 22, 2002 at 04:04:26AM -0700, nordin@glass.cse.ogi.edu wrote:
> nordin      2002/10/22 04:04:25 PDT
> 
>   Modified files:
>     libraries/Hugs       Prelude.hs 
>   Log:
>   Add explicit enumFromTo and enumFromThenTo for Ratio. From Ferenc Wagner.

Maybe it would be better to copy this out of the derived Report, except
maybe for the additional strictness.  But anyway its usefulness is
limited until Hugs implements floating point literals in the H98 way.
For example, consider the following expression (from the test suite):

	[-10.0,-9.9..10.0 :: Ratio Int]

In Haskell 98, this is the same as

	[-10%1,-99%10..10%1 :: Ratio Int]

but in Hugs we get

	[-10 % 1,-5190451 % 524288
	Program error: Ratio.%: zero denominator

because (-5190451 % 524288) + (52429 % 524288::Ratio Int) overflows.
(With Integer it doesn't, but the fractions are silly.)