Hi All,
I am playing around with the paren-shape syntax property
in order to use {} for polynomials.
The case {+ p q r ...} is causing me problems.
I have reduced the problem to the example below.
I'd like {+ 2 3 5} to expand to (* (* 2 3) 5) and thus evaluate to 30.
However as is {+ 2 3 5} expands to (#%app + (#%app * '2 '3) '5)
which gives 11.
What have I missed?
/Jens Axel
#lang racket
(module huh racket
(provide (rename-out [app #%app]))
(define-for-syntax (curlify stx)
(syntax-property stx 'paren-shape #\{))
(define-for-syntax (curly? stx)
(let ([p (syntax-property stx 'paren-shape)])
(and p (eqv? p #\{))))
(define-syntax (app stx)
(syntax-case stx (+)
[{_ + p q}
(curly? stx)
(syntax/loc stx (* p q))]
[{_ + p q r ...}
(curly? stx)
(curlify #'{app + (* p q) r ...})]
[(_ . more)
(syntax/loc stx (#%app . more))])))
(require 'huh)
{+ 2 3 5}
____________________
Racket Users list:
http://lists.racket-lang.org/users
