3 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.

Examples:

> (define c (arity/c 2))

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

#t

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

#f

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

#t

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

#t

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

#f