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Subject: Beginner's question.
From: "Alexander A. Vlasov" <zulu@galaradio.com>
To: caml-list@yquem.inria.fr
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Date: Thu, 27 Oct 2005 16:30:08 +0300
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Hello.

I'm making my first steps in OCaml and trying (just for expirience) to
implement a simple function which applies given function to all elements
of given list.
I successfully did it using if/then/else

let rec map func lst =
        if lst = [] then []
        else (func (List.hd lst)) :: (map func (List.tl lst))
;;

But I can't do it using pattern matching -- following function doesn't
work

let rec mapm func lst = function
        | ( _, [] ) -> []
        | ( _, head::tail ) -> (func head) :: (mapm func tail)
;;

I get type mismatch error: characters 39-55:
This expression has type 'a * 'b list -> 'c list but is here used with
type  'c list

But wait, ``map func (List.tl lst)''  in first example has the same
type, isn't it?
Both right parts in first and second example are, say, transformers from
a tuple ( something, list-of-something-else ) to list-of-something-else.

I understand that I missed something, so please tell me what.
and... thank you for your patience 8)



-- 
Best regards,
Alexander A. Vlasov.