On Thu, Aug 02, 2007 at 12:17:06PM -0700, brad clawsie wrote:
as far as i know, the haskell standard does not define a basic Int type that is limited to positive numbers.
Haskell 98 doesn't have such a type, no, but in today's libraries there is Data.Word.Word. Operations like subtraction will just wrap around when they would otherwise go negative, though ("All arithmetic is performed modulo 2^n").
for example, 'length' returns an Int, but in reality it must always return a value 0 or greater. a potential counter-argument would be the need to possibly redefine Ord etc for this more narrow type...
The main worry I can see with doing that is, would you need to keep explicitly converting between Int and Word? It might be possible to convert enough things to Word that it doesn't matter. You'd also break lots of programs, of course. Thanks Ian