From: "Alexander A. Vlasov" <zulu@galaradio.com>
To: caml-list@yquem.inria.fr
Subject: Beginner's question.
Date: Thu, 27 Oct 2005 16:30:08 +0300 [thread overview]
Message-ID: <1130419808.12902.13.camel@localhost.localdomain> (raw)
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.
next reply other threads:[~2005-10-27 13:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-27 13:30 Alexander A. Vlasov [this message]
2005-10-27 13:41 ` [Caml-list] " Luc Maranget
2005-10-27 14:40 ` Damien Doligez
2005-10-27 13:50 ` Jean-Christophe Filliatre
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