Re: the necessity of Lisp's Objects?

On Mon, 11 Feb 2008 02:56:22 -0600, rpw3@[EMAIL PROTECTED]
 (Rob Warnock) wrote:

>George Neuner  <gneuner2/@[EMAIL PROTECTED]
> wrote:
>+---------------
>| "David Formosa (aka ? the Platypus)" <dformosa@[EMAIL PROTECTED]
> wrote:
>| >Jon Harrop <usenet@[EMAIL PROTECTED]
> wrote: 
>| >> Actually, I can't think of any other languages that sup****t
recursive
>| >> anonymous functions anyway: none of Lisp, Scheme, SML, OCaml, F# and
>| >> Haskell do AFAIK.
>| >
>| >You can do anonymous recusion in Lisp and Scheme via letrec.  Any
>| >language where you can implement the Y-combinator you can get
>| >anonymous recursion.
>| 
>| Lisp doesn't have letrec - you use labels instead.  And technically
>| the functions are not anonymous because the forms require you to bind
>| or name them.  A function has to be named or symbol bound to be
>| recursive - else no way to refer to itself.
>+---------------
>
>Well, true, but you can keep the internal name from escaping by
>returning the function value, making it effectively "anonymous":
>
>    > (funcall
>       (labels ((self (x) (if (< x 2) 1 (* x (self (1- x)))))) #'self)
>       5)
>
>    120
>    > 

Yes, I suppose that is anonymous in the way John intended.

It's a little more verbose in Scheme:

 ((lambda (x)
   (let self ((x x)) 
     (if (< x 2) 1 (* x (self (- x 1))))))
  5)
 120

but I think the Scheme makes it a little clearer that there is a named
self referential function in an anonymous wrapper.  

George
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