why cannot assign to function call
Mark Wooding
mdw at distorted.org.uk
Tue Jan 6 09:12:19 EST 2009
Steven D'Aprano <steven at REMOVE.THIS.cybersource.com.au> wrote:
> I don't think so. Variables in algebra are quite different from variables
> in programming languages. Contrast the statement:
>
> x = x+1
>
> as a programming expression and an algebraic equation. As a programming
> expression, it means "increment x by one". But as an algebraic
> expression, it means "x is some value such that it is equal to one more
> than itself", and there is no solution to such an equation.
Surely there is. The solution is: 1 = 0 (and hence x is an -- no, /the/
-- element of the trivial ring).
> > and how several generations of computer languages, not to mention
> > the actual machine language those generated, behaved, before the current
> > crop.
>
> Sure. And?
Actally, this is true only for /very/ small values of `several'. There
was FORTRAN in 1957, with what you're calling the `named bins' model,
and I call assignment-is-copying, and Lisp in 1958, with the assignment-
is-pointer-diddling model.
-- [mdw]
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