cvs commit: fptools/libraries/base/GHC Real.lhs
Malcolm.Wallace at cs.york.ac.uk
Tue May 25 15:22:03 EDT 2004
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)
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