From: Sean O'Dell <sean@...>
Date: 2004-07-14T06:52:18+09:00
Subject: Re: Functional Ruby (Re: Why I don't use Ruby.)

On Tuesday 13 July 2004 14:37, Florian Gross wrote:
> Sean O'Dell wrote:
> >>> You're not supposed to have operators in a functional language,
> >>> like =, *, + and so on,
> >>
> >> BTW, an operator is usually nothing more than syntactic sugar for a
> >> function call.
> >
> > No, functional languages are not supposed to have operators.  That's
> > why they're called "functional languages"; they work like functions.
>
> Most of those operators are exactly like functions. = isn't if its an
> assignment operator, but if it is an comparison operator it indeed is
> compatible to the definition of the function.
>
> (Just because there's a different syntax for applying it doesn't mean
> that it's really different -- in fact in LISP + is just a function with
> a special name without any additional syntactic sugar.)

I know, but I was trying to illustrate how some people seem to get the rule 
against assignment operators confused with simple assignment.  You can assign 
values to variables in a functional language, you just have to do it through 
a function call; the assignment is permitted, however.  We're in agreement.

> >>> so you can't assign values "a=10" style, but you should be able
> >>> to say set(a, 10).
> >>
> >> Where is exactly the difference from a semantic POV ?
> >
> > Functional languages set the variable in a functional way.
>
> Functional languages don't enforce a specific syntax like function(arg1,
> arg2) etc., but they indeed specify that a function should have no side
> effects which means that the only way it should be able to interact with
> the outside world is by returning values. (Lambda calculus is the origin
> of functional languages and compared to computer languages its syntax is
> indeed very exotic.)

Unless something has changed, functional languages DO have to enforce a 
specific syntax; it must be functional (call, parameter).  The precise syntax 
is up to each language; lisp does it something like (set a 10) I believe, but 
another language could do it set(a, 10).  It really doesn't matter.

> I hope I was able to add something valuable.

You did, because I didn't realize that what I had said came out to sound as 
though I were asserting a specific syntax was needed.  The only real rule 
about assignment, I believe (been a long time), is that it must be in a 
functional form, and operators are not allowed (can't do a=10).

	Sean O'Dell