James Iry wrote:
No, C does not support functional programming. It is pretty much
impossible to write an interesting C program that does not mutate
things. That's not a condemnation of C, I still have a soft spot in
my heart for it, but it is a recognition of how C is deeply tied to
an imperative model of computation.
Still, I notice you haven't addressed the core of my argument:
functional programming languages and purely functional programming
existed before there were languages that could enforce the purity.
So insisting that language X is not functional because it does not
enforce purity is to redefine the phrase "functional programming
language" away from its historical roots in the Lisps and the MLs.
I thought Andrei's reply addressed it better than I could have.
There's a reason that Haskell is called a "purely functional
programming language" rather than just a "functional programming
language" and that is precisely to clarify one important dimension of
difference from the ML family. (It's actually called a "non-strict
purely functional programming language" to talk about another
important dimension of difference, but that's not what we're talking
about here.)
I don't disagree that it is possible, and even easy to write
imperative code in the (impure) functional languages in the Lisp and
ML families. But I do disagree with the contention that that makes
them anything but functional languages since the phrase "functional
programming language" was invented precisely to talk about their
ability to express purely functional code even if there was no
automated static proof of that purity.
I don't understand why C programs cannot be written that don't mutate
things (other than for initialization - even pure functional programs
initialize things).
