cvs commit: fptools/libraries/base/GHC Real.lhs

[Malcolm Wallace]

Simon Peyton Jones <simonpj at glass.cse.ogi.edu> writes:

>   Remove spaces around the "%" when showing ratios.
>   
>   This is not absolutely strictly according to the H98 report,
>   but it was suggested by Doug McIlroy
>   
>      According to the standard prelude, a list of Ratios prints like
>      this: [1 % 1,1 % 2,1 % 3,1 % 4], which strongly suggests the
>      grouping [1 % (1,1) % (2,1) % (3,1) % 4].
>   
>      Even standing alone outside of lists, the style is at odds with
>      mathematical custom.  When did you last see 1/2 written as 1 / 2?

I seem to remember that the rationale for spaces around the % operator
was to avoid lexing problems with non-canonically represented negative
Ratios, e.g. 2 % -3.  If written as 2%-3, the maximal munch rule
gives you 2 %- 3, which is not a Ratio.  However, perhaps you have some
other scheme for 'show'ing negatives, e.g. with parentheses?  2%(-3)

Regards,
    Malcolm