On 04/11/2010 09:25 AM, jhaase wrote:
(with-special-syntax ; unquoted vector
(let ((counter 345734817))
(lambda (stx)
(define (gensym)
(set! counter (+ counter 1))
(string->symbol (string-append "partial-app-gensym-"
(number->string counter))))
(define (last-pair ls)
(if (null? (cdr ls))
ls
(last-pair (cdr ls))))
(syntax-case stx ()
(#(f args ...)
(identifier? #'f)
(let loop ((oldargs #'(args ...))
(newargs '())
(lambdalist '()))
(syntax-case oldargs ()
((x)
(let ((lambdalist (reverse lambdalist)))
(if (eq? (syntax->datum #'x) '_)
(let ((sym (gensym)))
(if (null? lambdalist)
(set! lambdalist sym)
(set-cdr! (last-pair lambdalist) sym))
#`(lambda #,lambdalist
(apply f #,@(reverse newargs) #,sym)))
#`(lambda #,lambdalist
(f #,@(reverse (cons #'x newargs)))))))
((x y ...)
(if (eq? (syntax->datum #'x) '_)
(let ((sym (gensym)))
(loop #'(y ...)
(cons sym newargs)
(cons sym lambdalist)))
(loop #'(y ...)
(cons #'x newargs)
lambdalist)))))))))
(display (map #(+ _ 1) '(1 2 3 4)))
(newline)
(display (map #(* _ _) '(1 2 3 4) '(2 3 4 5)))
(newline)
(display (#(list _) 1 2 3 4))
(newline))
Juergen,
When I try the above example in Ikarus, it produces an error:
Unhandled exception
Condition components:
1. &who: walker
2. &message: "raw symbol encountered in output of macro"
3. &syntax:
form: (walker (display (map #(+ _ 1) '(1 2 3 4))))
subform: partial-app-gensym-345734818
4. &trace: #<syntax (walker (display (map #(+ _ 1) '(1 2 3 4))))>
5. &trace: #<syntax (with-special-syntax
Any ideas?
The dot and keyword examples worked fine by the way!
Ed
