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arity/ c

4 Contract utilities

 (require (planet untyped/unlib/contract))

Utilities for use with the PLT contract library.

(arity/c arity)  flat-contact?
  arity : natural?

Returns a flat contract that requires the input to be procedure that accepts the specified number of (non-keyword) arguments. The procedure may, in addition, accept more and/or fewer arguments and any number of keyword arguments.


  > (define c (arity/c 2))
  > (contract-first-order-passes? c (lambda (a b) (void)))


  > (contract-first-order-passes? c (lambda (a b c) (void)))


  > (contract-first-order-passes? c (lambda (a [b #f]) (void)))


  > (contract-first-order-passes? c (lambda (a b #:c c) (void)))


  > (contract-first-order-passes? c (lambda (a #:b b) (void)))