Re: showing Ratios

On Mon, Mar 1, 2010 at 1:29 AM, Jon Fairbairn wrote:

Iavor Diatchki writes:

...

Hi, I am not sure about the rationale but if you need a program/library which re-renders Show-able values with more spaces, so that they are more human readable,  I wrote one (http://hackage.haskell.org/package/pretty-show).  I find it very useful for debugging.

This comes up sufficiently often that perhaps the Show class should have readableShow that defaults to the same as show.

The thing I was curious about was why Show doesn't default to a more pretty output in the first place. I think it's appropriate that it doesn't insert extra newlines and whatnot, we can already get that in an orthogonal way with Show and reparsing with Language.Haskell.Syntax. I actually have a separate Pretty class which, unlike Show, is under no obligation to produce parseable or even unambiguous output. This is similar to Python's concept of separate str() and repr() functions. And then a separate 'pshow :: Show a => a -> String' produces 'show' output but with newlines and all lined up. The missing bit is a Pretty that produces a Text.PrettyPrint Doc, but this can all be done without recourse to modifying the Prelude.