Re: [Caml-list] Magic with fun (type t) ... ?

[Guillaume Yziquel <guillaume.yziquel@citycable.ch>]

Le Thursday 27 Jan 2011 à 07:13:42 (+0100), Alain Frisch a écrit :
> 
> There are two distinct problems here, neither of which has been
> introduced in 3.12.
> 
> First, the toplevel uses types to display exception arguments only
> when it knows exactly their type. Otherwise, there is a fallback
> heuristic to look at runtime tags.

But how does the toplevel determines types? My exception type was
perfectly declared and available in the .cmi file. Yet, before 3.12 I
got the <abstr> or similar displayed in the toplevel, and in 3.12 it
started segfaulting.

I'm simply wondering whether or not the heuristic gets triggered more
easily in 3.12 than it was before. It's just a gut feeling. Nothing I
can prove.

> Second, exception values values are compared structurally; this
> means that the constructors are compared textually and when they
> match, the arguments are compared even if they don't have the same
> type (yes, this can probably yield to segfaults).

My segfault wasn't about comparing two exceptions using generic
comparison, but merely not being able to display it in 3.12's toplevel.
 
> Cf:
> http://caml.inria.fr/mantis/view.php?id=1248
> http://caml.inria.fr/mantis/view.php?id=4531
> http://caml.inria.fr/mantis/view.php?id=4765
> http://caml.inria.fr/mantis/view.php?id=5087

Thanks for the background info.

-- 
     Guillaume Yziquel