Paul Rubin wrote: > Jeff Schwab <[EMAIL PROTECTED]> writes: >> Why not? They seem intuitive to me. I would find it weird if you >> couldn't have 0-tuple, and even weirder if you couldn't have a >> 1-tuple. Maybe my brain has been warped by too much C++ code. > > The idea is that a 2-tuple (of numbers, say) is a pair of numbers, a > 3-tuple is three numbers, and a 1-tuple is one number. That would > mean a number and a 1-tuple of numbers are the same thing, not > separate types.
No, that doesn't follow. A set with one element is not the same thing as that element, a sequence of one element is not the same thing as that element, and a tuple with one element is not the same thing as that element. > This is how most type systems treat tuples. I take it you have particular systems in mind, but I've never used a programming language that works that way. > Python does it a bit differently, treating tuples as something like > frozen lists, so they support subscripting, iterator interfaces and so > forth. There are practical advantages to doing it that way, but it > also leads to corners of oddness like the (a,) notation. That "oddness" has nothing to do with tuples-of-one being strange, nor does it imply that tuples are fundamentally different from other collection types. It is a historical accident of the fact that parentheses were already used to represent grouping for precedence by the time they were overloaded to represent tuples. If bare-paren tuples had not been allowed (as bare sets are not allowed), then there would be no ambiguity, and no need for the (a,) notation. -- http://mail.python.org/mailman/listinfo/python-list
