Re: [Chicken-users] bug(?) in macroexpansion

[Felix Winkelmann]

Panagiotis Vossos wrote:
> I am using chicken 1.0 and I think there is a bug in the way macros
> are expanded when hygenic macros are in use.  I don't have chicken
> running on this machine right now, but I remember that if you define a
> macro like:
>
> (define-syntax foo
>   (syntax-rules ()
>     ((_ x) (+ "baz" x))))
>
> , then (foo 10) gets expanded as:
>
> (+ '"baz" '10)
>
> when it should be:
>
> (+ "baz" 10).
>
> I came across this when trying to compile library.scm with -hygienic
> and it complained about incorrect use of inline_allocate or something.
>
> Am I missing something or is it indeed a bug?

It's not really a bug. The syntax-case expander automatically
quotes all constants, so if you try

>>> ,x (foo "baz" abc)

Your will get

(+ '"baz" abc)

i.e. the expander is fully aware of what has to be quoted and what
not. This *might* give problems with certain Chicken-specific
forms that use non-evaluated arguments (I just stumbled across
an issue with `define-constant' a couple of days ago).
Apparently `inline_allocate' has to be changed to handle this
behaviour, too. Perhaps more special forms have to be adapted.

Thanks for the tip.


cheers,
felix