Should Dylan show up in this list of functional languages? http://dmoz.org/Computers/Programming/Languages/Functional/

Well, it works for *me*. ;-)

A lot of my Dylan code is written in a purely functional style.
Dylan does not preclude doing this, and in fact, it is easy to do so.

However, purists could rightfully point out that Dylan does not *require* a functional style. Me, I think it should be on the list, but I'm not a purist...

If Common Lisp and Scheme and OCaml are there (which they are) then Dylan certainly should be too.

Like them Dylan has all the features needed to be used in a purely functional style, but doesn't force you into programming that way.

What is a "functional language"?

To me, it has less to do with being side-effect free than with providing "first class" functions.
I would also add block structure and lexical scope as criteria to really be a functional language.

Does Dylan have first class functions, block structure, and lexical scope? Yes, so I'd put it in there without hesitation.

> If Common Lisp and Scheme and OCaml are there (which they are)
> then Dylan certainly should be too

I'm mostly an OCaml programmer these days, and I'd agree OCaml is (not just) a functional programming language, as is Dylan.

> Like them Dylan has all the features needed to be used in a purely > functional style, but doesn't force you into programming that way.

A more interesting question IMO is to what extent a functional style is used in common Dylan programming. My OCaml style is largely functional but there is almost *always* some bit of imperative code, and the use of exceptions (which some people, not me, consider non- functional).

Neelakantan Krishnaswami

Honestly, my Dylan code is more functional than my Ocaml code. This is because I find it easier to write in a state-passing or monadic style in Dylan than in Caml.

I find Dylan nicer for writing state-passing code because of a nasty habit: I care about memory allocation. Dylan's multiple return values can be stack allocated, whereas using a tuple won't be. Even though I *know* that I shouldn't care, I do. :) The combination of generic functions makes a modular monadic style almost ridiculously easy to do. I tend to cheat a bit, and use macros to eliminate the overhead of a monadic style, too.