[gambit-list] syntax-case and procedures with keyword parameters
Marc Feeley
feeley at iro.umontreal.ca
Sun Mar 4 13:20:12 EST 2012
On 2012-03-04, at 11:22 AM, Álvaro Castro-Castilla wrote:
> Marc,
>
> I see.
> The only reason I miss syntax-rules is for some SRFIs and libs like
> Kanren, completely implemented as syntax-rules. Otherwise I'm happier
> with define-macro :)
>
> Thanks for your reply
By the way, I should have mentionned in my previous message that when using the -:s switch, you still have access to ##lambda which does support DSSSL parameter lists. The form ##lambda has the same syntax as lambda, but it is not under the control of the psyntax expander (which defines lambda as a macro).
So you can do this:
% gsi -:s
Gambit v4.6.4
> (define f (lambda (a b #!optional (c (+ a b)) #!rest d) (list a b c d)))
*** ERROR -- invalid parameter list in (lambda (a b #!optional (c (+ a b)) #!rest d) (list a b c d))
> (define f (##lambda (a b #!optional (c (+ a b)) #!rest d) (list a b c d)))
> (f 0 1 2 3 4)
(0 1 2 (3 4))
> (define f (##lambda (a b #!key (c (+ a b)) #!rest d) (list a b c d)))
> (f 11 22)
(11 22 33 ())
> (f 11 22 c: 99)
*** ERROR IN (console)@6.10 -- Unbound variable: c:
1>
> (f 11 22 (string->keyword "c") 99)
(11 22 99 ())
> (define c: (string->keyword "c"))
> (f 11 22 c: 99)
(11 22 99 ())
Marc
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