RE: [Caml-list] OCaml's variables

[David Allsopp <dra-news@metastack.com>]

oliver wrote
> Hi,
> 
> On Sat, May 25, 2013 at 01:49:46PM +0200, Gabriel Scherer wrote:
> > The name "variable" has been used for centuries by the mathematicians
> > to denote exactly names that refer to values (of course immutable
> > values, we're talking about mathematical objects her). There is no
> > point in trying to change it because some people conflate this notion
> > with mutability.
> 
> Hmhhh.
> "Some" people? As far as I remember, I heard these arguments quite often.

Some does not mean few. You appear to be trying to split hairs without a sufficient command of English. Once upon a time I would have prefixed that "With respect", but various Internet memes mean that most people now know what a British person actually means when they say that ;o)

> > (When you write (x + 1), the value denoted by "x" is an unknown that
> > depends on the context/environment; in particular it may vary when
> > used in different contexts.)
> >
> > The name "variable" is also used in the expression "type variable",
> > which denotes for example the 'a in
> >   val id : 'a -> 'a
> > and which is clearly not associated to any form of mutation.
> [...]
> 
> Hmhhh, and what about imperative languages?
> What part did they broke?
> And why did they "misuse" the word "variable" and in which way?
>
> Is it because of mutability, which may break all these used "mathematical
> metaphors"?
> 
> Can you elaborate on why "variables" are the wrong term or a 2bad" term in
> imperative languages and not in functional languages?

There is no misuse and nothing broken - it is merely that when talking about imperative languages the word "variable" is typically where "mutable variable" is meant (because immutability is not usually of interest). When first teaching functional languages to people who are probably already familiar with imperative languages, one often chooses to eliminate the use of the word variable. This is because it can be confusing when trying to convey how to think functionally versus imperatively (a child's trick: if the student uses the word variable they are probably thinking of a reference cell and hence not functionally - so you steer the argument by "banning" the word variable from the conversation). Once you actually have an understanding of functional thinking, the elimination of the word variable becomes unnecessary.

The OCaml Language Specification is most certainly not a document intended for a beginner either to OCaml or functional programming - an obsessive elimination of the word variable would likely make the text less clear to those who will actually be reading it.


David