From: hubert.fauque@wanadoo.fr
To: caml-list@inria.fr
Subject: Re: Typing-problem
In-Reply-To: aXl's message of "Sun, 30 May 1999 17:24:50 +0200 (MET DST)"
Date: 31 May 1999 14:42:20 +0200
aXl <krauth@fmi.uni-passau.de> writes:
> Hi,
> why is in the following example b of type "string -> string" ?
because a is of type string->string and b=a
>
> let a = id id;;
> let b = a;;
> a "foo";;
> (* until here it's covered by the faq's *)
> b;;
let b = a defines a new name (b) for the object designed by a;
it doesn't construct a new object, and it doesn't do a new call (id id);
it is different from
let a = id id;;
let b = id id;;
The Caml let ..= .. is different from the assignment in C or Pascal;
in C if you write
a=b;
there is a variable "a" which already as a place
in memory, and a=b means: copy the memory location of b to a;
in Caml let defines a new name; it's the right of the = which may
construct a new object; that's why
let a = id id
let b = a
is different from
lat a = id id
let b = id id
Hubert
hubert.fauque@inria.fr
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