On Jun 29, 2014, at 8:44 PM, Roman Klochkov <kalimeh...@mail.ru> wrote:
> > procedure-has-arity is not needed. I can write: > > (define/contract (test f) (-> (or/c > (-> input-port? any/c any) > (-> input-port? any/c any/c any) > (-> input-port? any/c any/c any/c any) > (->* (input-port? any/c) #:rest list? any)) > any) > 1) > > (test (λ (x y) 2)) > 1 > procedure-has-arity is needed if f is something like (λ (x y . rst) x). In this case or/c would report an error because f would match more than one of the contracts in the or/c. That’s also why it needs to be procedure-has-arity, and not procedure-arity-includes. > But I need any number of args, more than two. I can, of course write > something like > (define-syntax (make-contract stx) > (syntax-case stx () > [_ (with-syntax ([(CLAUSES ...) (for/list ([i 100]) ;;; hope 100 enough > many > #`(-> input-port? any/c > #,@(for/list ([j i]) > #'any/c)))]) > #'(or/c CLAUSES ... (->* (input-port? any/c) #:rest list? any)))])) > > But it is very slow and clumsy. > In that case, you could use this: http://docs.racket-lang.org/reference/Building_New_Contract_Combinators.html > > Sun, 29 Jun 2014 18:43:15 -0500 от Robby Findler > <ro...@eecs.northwestern.edu>: > Why isn't: > > (->* (input-port? any/c) #:rest list? any) > > by itself the contract that you want? > > Robby > > > On Sun, Jun 29, 2014 at 12:08 PM, Alexander D. Knauth > <alexan...@knauth.org> wrote: > > 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 <kalimeh...@mail.ru> 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 > > > > > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > > > > -- > Roman Klochkov
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