[Python-Dev] PEP239 (Rational Numbers) Reference Implementation and new issues (original) (raw)

Tim Peters tim.one@comcast.net
Wed, 02 Oct 2002 21:21:54 -0400

[Andrew Koenig]

Much as I like APL, I'd rather use Scheme's numeric model.

[Guido]

I've heard that before, but I've also heard criticism of Scheme's numeric model. "It works in Scheme" doesn't give me the warm fuzzy feeling that it's been tried in real life.

We've been thru this before too , but it doesn't even work in Scheme -- the Scheme std is too permissive in what it allows conforming implementations to get away (rationals aren't required; unbounded ints aren't required; ints period aren't required; while an "exact" flag is required, it has no portable mandatory semantics outside the (also undefined) range of numbers needed to index vectors; etc). Real number-crunchers have no use for it even in a full implementation, as it doesn't have a way to force precision-vs-space tradeoffs without extending the language. There's a reason the NumPy folks never bug you for Scheme features .