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Message-ID: <48727F44.8010500@ed.ac.uk>
Date: Mon, 07 Jul 2008 21:40:36 +0100
From: Jeremy Yallop <jeremy.yallop@ed.ac.uk>
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To: Fabrice Marchant <fabricemarchant@free.fr>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] functions' recursive construction
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X-Spam: no; 0.00; recursive:01 coq:01 curried:01 lambda:01 lambda:01 wrote:01 caml-list:01 cond:02 define:02 define:02 off-topic:02 lisp:02 args:05 args:05 scheme:05 

Fabrice Marchant wrote:
> After Coq, maybe could we program this in Lisp ?

Yes, although this is rather off-topic.  Here are two solutions in 
(rather rusty) Scheme, both zero-based again.  A curried version:

   (define (f n)
     (cond
      ((zero? n) (lambda (x) x))
      (#t        (lambda (_) (f (- n 1))))))

Now

   > ((f 0) 1)
   1
   > (((((f 3) 1) 2) 3) 4)
   4

An uncurried version:

   (define (f n)
     (lambda args (list-ref args n)))

Now

   > ((f 0) 1)
   1
   > ((f 3) 1 2 3 4)
   4

Jeremy.