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") |
(define-struct toy (color) #:transparent) |
(define (build-toys n) |
(for/list ([i (in-range n)]) |
(make-toy 'blue))) |
(define (repaint t col) |
(make-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 @.