14.5 Whole-module Signatures and Units
In programs that use units, modules like "toy-factory-sig.rkt" and "simple-factory-unit.rkt" are common. The racket/signature and racket/unit module names can be used as languages to avoid much of the boilerplate module, signature, and unit declaration text.
For example, "toy-factory-sig.rkt" can be written as
#lang racket/signature build-toys ; (integer? -> (listof toy?)) repaint ; (toy? symbol? -> toy?) toy? ; (any/c -> boolean?) toy-color ; (toy? -> symbol?)
The signature toy-factory^ is automatically provided from the module, inferred from the filename "toy-factory-sig.rkt" by replacing the "-sig.rkt" suffix with ^.
Similarly, "simple-factory-unit.rkt" module can be written
#lang racket/unit (require "toy-factory-sig.rkt") (import) (export toy-factory^) (printf "Factory started.\n") (struct toy (color) #:transparent) (define (build-toys n) (for/list ([i (in-range n)]) (toy 'blue))) (define (repaint t col) (toy col))
The unit simple-factory@ is automatically provided from the module, inferred from the filename "simple-factory-unit.rkt" by replacing the "-unit.rkt" suffix with @.