Original bug ID: 1927
Reporter: administrator
Status: closed
Resolution: fixed
Priority: normal
Severity: feature
Category: ~DO NOT USE (was: OCaml general)

Bug description

On 12.11.2003 04:49, Damien Doligez wrote:

Yes, but. In 3.06, [] will never be removed from the weak array, and
you will keep your helper data forever.

But that is reasonable semantically - since for all we know some
reachable memory location can have [] in it, so we need to keep it
forever. Note that for the same reason the helper data needs to stay
around forever anyway, but now the implementation just got much uglier.

Basically, we used to have a very nice and completely polymorphic
weak_memo module (that solves the following problem - if you have an
arbitrary mutually-recursive data type that you are converting into an
"isomorphic" one, how do you set it up so that equal inputs are mapped
to the same output, and the whole process takes linear time); and in
3.07 this module needs to include various calls to Obj to be able to
figure out whether the output happens to be an unboxed value.

In other words, 3.06 allowed things to stay completely polymorphic,
while 3.07 requires Obj hacks. Very unfortunate...

--
Aleksey Nogin

Home Page: http://nogin.org/
E-Mail: nogin@cs.caltech.edu (office), aleksey@nogin.org (personal)
Office: Jorgensen 70, tel: (626) 395-2907