Re: srfi-18 and the vm

[ludo@gnu.org (Ludovic Courtès)]

Andy Wingo <wingo@pobox.com> writes:

> On Fri 22 May 2009 17:10, ludo@gnu.org (Ludovic Courtès) writes:
>> Andy Wingo <wingo@pobox.com> writes:
>>
>>> I'm catching up with mail. On my syncase-in-boot-9 branch, I enabled
>>> compilation of srfi-18 and fixed a bug in it regarding multiple-value
>>> returns. Now I just ran the srfi-18 test like 100 times in a row and it
>>> didn't show any strange errors. Yaaaay!
>>
>> What kind of "strange errors" would it lead to before?
>
> Random ones based on races, as code was lazily memoized from multiple
> threads at once.

OK (I thought you were referring to errors related to multiple-value
returns.)  Then, indeed, yaay!

> Indeed. The VM truncates multiple values, but here we were doing a (let
> ((x (values))) something x), which returned 0 values to a continuation
> needing a value, raising a valid error. Fixed that in the original
> source code.
>
> In addition, we were sometimes getting 0 values in a for-effect context,
> which the GHIL->GLIL compiler didn't support. Like this:
>
>   (begin (call/cc (lambda (k) (k))) 10)
>
> I've fixed this in the tree-il->glil compiler.

Thanks for the explanation.

Ludo'.