From: Yves Bertot <Yves.Bertot@sophia.inria.fr>
To: Damien Guichard <alphablock@orange.fr>
Cc: "caml-list@yquem.inria.fr" <caml-list@yquem.inria.fr>
Subject: Re: [Caml-list] Error: This function is applied to too many arguments,maybe you forgot a `; '
Date: Mon, 04 Aug 2008 07:58:03 +0200 [thread overview]
Message-ID: <48969A6B.5010005@sophia.inria.fr> (raw)
In-Reply-To: <20080804005824.5FA4480000A0@mwinf2804.orange.fr>
To be more precise, Ocaml being a functional language, any function,
when applied
to one argument, may return a new function which can in turn be applied
to another
argument.
Thus if you write :
(a (b)) (c),
Ocaml (and most other functional programming languages), understand that
a(b) is supposed to be a function, that returns another function, then
applied to c.
In practice, this trick is used extensively throughout functional
programs, so
that placing parentheses around arguments would result in a humongous number
of parentheses. For this reason, a new convention for parentheses was
enforced:
you don't put any parentheses around function arguments, unless it is
necessary
for disambiguation (for instance, if you want b to be applied to c, and
you don't
place parentheses around the function part, so that (a(b))(c) is simply
written
a b c
This means : a applied to b, and then to c,
Now, if you want "a applied to the result of applying b to c", you write
a (b c)
Please note there are no parentheses around c.
In practice, most functions taking several arguments are described in this
manner, instead of being described as function taking a pair as argument.
This is known as "currification" because Curry was one of the early
mathematicians
to advocate the idea that mathematics (and programming) could be described
with only one-argument functions.
In your case, both print_int and fac are one argument functions, as can
be seen from
their type.
Yves
next prev parent reply other threads:[~2008-08-04 5:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-04 1:00 Damien Guichard
2008-08-04 5:58 ` Yves Bertot [this message]
-- strict thread matches above, loose matches on Subject: below --
2008-08-04 0:46 Error: This function is applied to too many arguments, maybe you forgot a `;' Ben Aurel
2008-08-05 12:11 ` [Caml-list] Error: This function is applied to too many arguments, maybe you forgot a `; ' Richard Jones
2008-08-05 13:29 ` Peng Zang
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