]>
Oops, I pushed "send" button too early.
Le 27 oct. 09 à 19:38, Vincent Aravantinos a écrit :
> Le 27 oct. 09 à 19:24, Jake Donham a écrit :
>
>> On Tue, Oct 27, 2009 at 3:28 AM, Marc de Falco <marc@de-falco.fr>
>> wrote:
>>> The following code :
>>> type 'a p = R of 'a t | E of float
>>> and 'a t = { mutable p : 'a p; c : 'a }
>>> let f =
>>> let x = sqrt(2.0) in
>>> fun () -> { c = `A; p = E 0.0 }
>>>
>>> generates the error :
>>> The type of this expression, unit -> _[> `A ] t,
>>> contains type variables that cannot be generalized
>>>
>>> but if I change the x definition to "let x = 2.0 in" then it works.
>>
>> I think this is just the value restriction. The type of f is
>> generalized only if the right hand side is a value (rather than an
>> expression needing some computation); in your examples the one that
>> fails is not a value, the others are. It looks like there is a
>> relaxation to allow let bindings which are themselves values.
>
> With the -dlambda option, the "sqrt(2.0)" version gives:
> (let
> (f/92
> (let (x/93 (caml_sqrt_float 2.0))
> (function param/94 (makemutable 0 [1: 0.0] 65a))))
>
> whereas the "2.0" version gives:
> (let (f/96 (let (x/97 2.0) (function param/98 (makemutable 0 [1:
> 0.0] 65a))))
>
> i.e. this last version is inlined.
Do you think this can give a hint?
V.