Re: [Caml-list] Error: This function is applied to too many arguments,maybe you forgot a `; '

Re: [Caml-list] Error: This function is applied to too many arguments,maybe you forgot a `; '

[Damien Guichard]

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Hi,

This line:

    print_int fac(6);;

Can be read as:

    print_int fac 6;;

That is 2 arguments whereas print_int expects exactly 1 argument.

The corrected line is:

    print_int (fac 6);;

Note that function application is just juxtaposition, parenthesis are unneded.

Regards,

- damien






hi
I try to make my first steps with Ocaml and I have some difficulties.
I know there is a second list for "Ocaml Beginners" but its running on
Yahoo and the membership confirmation takes a while ...

So let me ask you, what is wrong with this code

let rec fac n = if n >  1 then n * fac (n-1) else 1 ;;
print_int fac(6);;

No matter if I compile this with ocamlc or run the commands with
ocaml, I always get the error:
/////////////////////////////////////////////////////////////////
File "ifelse.ml", line 2, characters 0-9:
This function is applied to too many arguments,
maybe you forgot a `;'
///////////////////////////////////////////////////////////////////

What is the problem here? Adding an additional ; doesn't help of course.

thanks
ben

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Re: [Caml-list] Error: This function is applied to too many arguments,maybe you forgot a `; '

[Yves Bertot]

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

Re: [Caml-list] Error: This function is applied to too many arguments, maybe you forgot a `; '

[Peng Zang]

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On Tuesday 05 August 2008 08:11:40 am Richard Jones wrote:
> On Sun, Aug 03, 2008 at 08:46:32PM -0400, Ben Aurel wrote:
> > print_int fac(6);;
>
> Read this: http://www.ocaml-tutorial.org/the_basics
>
> Rich.


Second that.  You really should take a look at that.  Also, this is a great 
resource as well:

  http://www.cs.caltech.edu/courses/cs134/cs134b/book.pdf

You can read that online or print out chapters for offline reading.


Peng
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Re: [Caml-list] Error: This function is applied to too many arguments, maybe you forgot a `; '

[Richard Jones]

On Sun, Aug 03, 2008 at 08:46:32PM -0400, Ben Aurel wrote:
> print_int fac(6);;

Read this: http://www.ocaml-tutorial.org/the_basics

Rich.

-- 
Richard Jones
Red Hat