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

David Abrahams dave@boost-consulting.com
07 Oct 2002 22:29:21 -0400

Guido van Rossum <guido@python.org> writes:

> I liked 2r/3 because it gives the sense that r/ is the rational > division operator, where // is the whatever-the-hell-it-is division > operator. I don't know if it works in the grammar to be able to say > > x r/ y > > though. Does it?

That would require changes to the tokenizer. But I am against r/ on different grounds: it's not the kind of grouping of symbols that one would expect. People are used to 12L, 1j and then it's a small step to 2r.

You're right. And now that I look at it, if 2r is a rational with value 2, and if you can divide ints by rationals, then 1/2r makes a lot of sense. I wasn't looking at it that way (but I am now, and liking it).

There were also precedents for r"..." and u"...": C's w"...". If you want a precedent for 2/, you'd have to search in Lisp or Forth or other (nearly) grammar-less languages.

Oh, please, don't remind me about those funky Forth symbols. I guess it has less to do with grammar than with lexemes, though.

-- David Abrahams * Boost Consulting dave@boost-consulting.com * http://www.boost-consulting.com