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Why doesn't ocamlopt detect a missing ; after failwith statement?
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Date: 2004-11-26 (19:36)
From: Michal Moskal <michal.moskal@g...>
Subject: Re: [Caml-list] Why doesn't ocamlopt detect a missing ; after failwith statement?
On Fri, 26 Nov 2004 08:08:57 +0100, Nicolas Cannasse <warplayer@free.fr> wrote:
> > P.S.
> > I believe the problem with failwith is solvable, albeit rather
> > complicated. The idea is that you want to be warned when you apply a
> > function of type (\forall 'a. 'a) to something, because no such
> > function may exist, so that this application will never actually take
> > place.
> >
> > This could be done attempting to generalize the type of the function,
> > once we now it is a type variable.
> > I'll have a try.
> Wouldn't that break Obj.magic ? I can't see a clear solution to this
> problem, unless enabling arity specification into polymorphic variables :
> 'a.0 for example, but this would also break something like :
> let f x = if x then failwith "error" else fun() -> x

No, because here you're applying functional type that got unified with
the variable, and not the ununified type variable itself.

> I guess it's more like a syntax problem. For example having parenthesis for
> function calls à la C would disable any ambiguity.

And this is why an empty word as an function application is wrong :-)

: Michal Moskal ::: http://nemerle.org/~malekith/ :: GCS !tv h e>+++ b++
: ::: Logic is a nice contrast to the Real World. :: UL++++$ C++ E--- a?