Re: [Chicken-hackers] testcase -strict-types

[Jörg F . Wittenberger]

On Mar 24 2013, Moritz Heidkamp wrote:

> Peter Bex <address@hidden> writes:
> > As I understand it, strict-types declares variables to never change
> > their types.  So once it's looked at the initial declaration of the
> > variable, it assigns it a type of null, and then it can never change.
> >
> >     -strict-types assume variable do not change their type
> >
> > The set! would change the type from NULL to LIST (or maybe PAIR),
> > invalidating that assumption.
>
> Ah, very good, that should explain it. I somehow had it remembered as
> "assume functions are always called with correctly typed arguments" or
> something. Should have RTFM :-)

I guess the problem is something different.

Though in a way the explanation is correct.  -strict-types assumes
'() to be null from the initialization.  Short of a way to declare
the type of foobar as (list-of <whatever>) this fails when it's used
as the initial and correct value of type (list-of <whatever>) with
zero length.

What the optimizer should do is to see into the doloop and notice
the ambiguous type null being refined to a list.


Find attached two more variants.  strcttps2.scm, which convinces
chicken to do the right thing, ans strcttps2.scm, which fails
the other way around.


Best

/Jörg





......

strcttps2.scm
Description: strcttps2.scm

strcttps3.scm
Description: strcttps3.scm