Chris Angelico <ros...@gmail.com>: > On Wed, Nov 25, 2015 at 11:48 PM, Marko Rauhamaa <ma...@pacujo.net> wrote: >> I think "binding" is too fancy a word to be used with conventional >> programming languages like Python. If your programming language has >> an assignment statement, "binding" is even nonsensical. Consider: >> >> def f(x): >> x += 1 >> return 2 * x >> >> Now we would have this reduction: >> >> f(7) >> => >> 7 += 1; return 2 * 7 >> >> because "x" would be bound to "7" everywhere in the function body. > > This is exactly the sort of problem that inevitably happens when you > try to extend mathematics into programming. Most branches of > mathematics are simply looking at pure, eternal statements of truth; > if once you discover (or decide) that x is equal to 7, you can > perfectly substitute one for the other in any context. There is no > chronology - x has always been equal to 7, you just didn't know it > until now. It's possible to write code this way, and there are > benefits to it, but as soon as you have an assignment operator, you're > introducing a whole aspect of chronological truth that math lacks, so > some concepts ARE going to need to be modified. > > However, that doesn't stop us from making use of terminology, where > it's helpful.
I think that's the point. Binding is a concept of a formal (textual) substitution algorithm, which Python's assignment is not. Variable-binding mechanisms occur in different contexts in mathematics, logic and computer science. In all cases, however, they are purely syntactic properties of expressions and variables in them. <URL: https://en.wikipedia.org/wiki/Free_variables_and_bound_variable s#Formal_explanation> Marko -- https://mail.python.org/mailman/listinfo/python-list
