I reformulate my problem: I need to make a chaperone, that checks only type of first arg. Is it possible?
If yes, I'll sumply make something like (define (arity>=/c x) (λ (proc) (define arity (normalize-arity (procedure-arity proc))) (define max-arity (if (list? arity) (car (reverse arity)) arity)) (or (arity-at-least? max-arity) (>= max-arity x)))) (and/c (arity>=/c 2) (check-first-arg input-port?)) Sun, 29 Jun 2014 13:08:06 -0400 от "Alexander D. Knauth" <[email protected]>: >You can use or/c to do this, as long as you guard them like this so that no >more than one contract matches at a time: >(or/c > (and/c (procedure-has-arity/c 2) (-> input-port? any/c any)) > (and/c (procedure-has-arity/c 3) (-> input-port? any/c any/c any)) > (and/c (procedure-has-arity/c 4) (-> input-port? any/c any/c any/c any)) > (->* (input-port? any/c) #:rest list? any) > ) > >Or, you could use if/c from unstable/contract, or define a cond/c macro like >this: >(require unstable/contract) >(define-syntax cond/c > (syntax-rules (else) > [(cond/c) none/c] > [(cond/c [else else-c]) > else-c] > [(cond/c [pred then-c] clause ...) > (if/c pred > then-c > (cond/c clause ...))])) > >(cond/c [(procedure-has-arity/c 2) (-> input-port? any/c any)] > [(procedure-has-arity/c 3) (-> input-port? any/c any/c any)] > [(procedure-has-arity/c 4) (-> input-port? any/c any/c any/c any)] > [else (->* (input-port? any/c) #:rest list? any)]) > >By the way it has to be procedure-has-arity/c, not procedure-includes-arity/c: >(define (procedure-has-arity/c arity) > (define normalized-arity (normalize-arity arity)) > (flat-named-contract > `(procedure-has-arity/c ,normalized-arity) > (λ (f) > (and (procedure? f) > (arity=? (procedure-arity f) normalized-arity))))) >On Jun 29, 2014, at 8:00 AM, Roman Klochkov < [email protected] > wrote: >>How to make a contract, that accepts >>(-> input-port? any/c any) >>(-> input-port? any/c any/c any) >>(-> input-port? any/c any/c any/c any) >>... >>and >>(->* (input-port? any/c) #:rest list? any) >> >>So theare should be at least two args and first arg should be input-port. >> >>-- >>Roman Klochkov ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users > -- Roman Klochkov
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