I like to make syntax-optimized functions.
(define-syntax (square stx)
(syntax-case stx (square expt)
[(square (square expr)) #'(expt expr 4)]
[(square (expt expr n)) (if (number? (syntax-e #'n))
#`(expt expr #,(* (syntax-e
#'n) 2))
#'(expt expr (* n 2)))]
[(square x) #'(* x x)]
[square #'(lambda (x) (* x x))]))
So I can write (square (expt x 5)) and have evaluate (expt x 10) and I can
write (map square '(1 2 3)) and it is also works.
But I dislike to repeate the body of the function in last two cases.
I tryed
(define-syntax (square stx)
(let ([body #'(* x x)])
(syntax-case stx (square expt)
...
...
[(square x) body]
[square #'(lambda (x) #`body)]))
but hygiene prevents me from that: x: unbound identifier in module in: x How
can I bind template body with some variable? Or how to rewrite the syntax to
evade duplication?
--
Roman Klochkov
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