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Date: Tue, 17 Sep 2002 08:23:01 -0700
Subject: Re: [Caml-list] function polymorphic in number of arguments?
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Cc: Noel Welsh <noelwelsh@yahoo.com>
To: <caml-list@pauillac.inria.fr>
From: Quetzalcoatl Bradley <qbradley@blackfen.com>
In-Reply-To: <20020917084045.46976.qmail@web11206.mail.yahoo.com>
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Actually I wanted to pass the same parameters to both g and h but your 
solution is obvious and simple.  if all the arguments of g and h are 
curried then my generic function always has "one" argument, the tuple 
of arguments to g and h, regardless of the size of the tuple.

So my function is
let f a b x = a x; b x;;

and a two argument "a" or "b" would be
let a x = match x with (i,j) -> print_string ("i" ^ "j");;

and I can call it e.g.

f a a ("z","x");;

Thanks,

Quetzalcoatl Bradley
qbradley@blackfen.com

On Tuesday, September 17, 2002, at 01:40  AM, Noel Welsh wrote:

> You can't have multiple arity functions or tuples in
> O'Caml, but you can curry the functions before calling
> them which is how I'd solve your problem.  You want to
> write something like:
>
>  fun f g h a1 a2 b1 b2 =
>    g a1 a2 ; h b1 b2
>
> with varying numbers of a and b.  Instead you can
> write:
>
>
>  fun f g h a1 b1 =
>     g a1; h b1
>
> and curry additional parameters when you call the
> function:
>
>  f (g a2) (h a2)
>
> This gets the same effect.  Alternatively you can use
> Scheme/Lisp which supports varying arity functions and
> has a handy apply function, for applying varying
> numbers of arguments to a function.
>
> Noel
> --- Quetzalcoatl Bradley <qbradley@blackfen.com>
> wrote:
>> Suppose all the parameters were curried.  Unless I
>> could operate on
>> tuples like they were lists then I would still be in
>> the same boat.  I
>> suppose if there was a tuple->list conversion
>> function I could achieve
>> the effect I desire.  Is there such an operation?
>>
>> Thanks,
>>
>> Quetzalcoatl Bradley
>> qbradley@newheights.com
>
>
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