On Thu, 23 Feb 2006, Eric Cooper wrote:

> On Thu, Feb 23, 2006 at 06:28:48PM +0100, Frdric Gava wrote:
>> is anybody can semantically explain why this 2 types are differents ?
>>
>> # type t=A of int*int and  t'= B of (int*int);;
>> type t = A of int * int
>> and t' = B of (int * int)
>> [...]
>> I understand that it'is force you to have a pair for A and not just a value
>> of type pair but why this restriction ? It is not easy to explain why
>> int*int <> (int*int).
>
> See section 18.3.4 of the manual -- the distinction allows the runtime
> representation of t to avoid a level of indirection.  And since the
> runtime representations are different, the types have to be different.

See also how this issue is handled by the revised syntax:
   http://caml.inria.fr/pub/docs/manual-camlp4/manual007.html#toc24


Martin

--
Martin Jambon, PhD
http://martin.jambon.free.fr

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