Re: [Chicken-users] Syntax of case expressions

[Elf]

no, actually, i get lots of errors about 'quote' being an invalid 
value to car in macros.

to demonstrate:

(define foo 'quote)
(case foo
    ('a 1)
    (else 2))  => 1

the proper behaviour in this case, btw, has not yet been given.

(define foo 'a)
(case foo
    ((a)  1)
    (else 2))

is the r5rs semantics of case.

will you believe me now when im telling you that chicken is not resolving the
symbols properly in macro forms?

-elf


On Thu, 28 Feb 2008, Ivan Raikov wrote:

>  Remember that in Scheme, (define foo 'a) is a shortcut for
> (define (define foo (quote a))) -- quote is a special form, and not
> a part of the literal. So you in your case statement you are not
> matching the symbol a, you are actually matching the symbol 'a (the
> apostrophe is treated as a literal in the case statement). Your first
> example should actually be:
>
> (case foo
>  ((a) 1)
>  (else 2))
>
> Chicken works as expected with that code.
>
>  -Ivan
>
> Matt Gushee <address@hidden> writes:
>
> > Hi, all--
> >
> > I have just written a 'string-case' macro--it is supposed to behave
> > just like case, except that it uses string=? in place of eqv? as its
> > equality predicate. But in the course of writing test cases, I have
> > encountered a surprise: the Chicken version of case appears to be
> > non-compliant with R5RS.
> >
> > The spec says
> >
> >   Syntax: <Key> may be any expression. Each <clause> should have the
> >     form
> >
> >   ((<datum1> ...) <expression1> <expression2> ...),
> >
> > But the syntax implemented in Chicken appears to be
> >
> >   (<datum> <expression1> <expression2> ...)
> >
> > E.g.:
> >
> > csi> (define foo 'a)
> > csi> (case foo
> > --->    (('a) 1)
> > --->    (else 2))
> > 2
> > csi> (case foo
> > --->   ('a 1)
> > --->   (else 2))
> > 1
> >
> > Or have I misunderstood something?
>
>
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