<import spec>、<export spec> の様々な例。
(library (stack) (export make push! pop! empty!) (import (rnrs) (rnrs mutable-pairs)) (define (make) (list ’())) (define (push! s v) (set-car! s (cons v (car s)))) (define (pop! s) (let ([v (caar s)]) (set-car! s (cdar s)) v)) (define (empty! s) (set-car! s ’()))) (library (balloons) (export make push pop) (import (rnrs)) (define (make w h) (cons w h)) (define (push b amt) (cons (- (car b) amt) (+ (cdr b) amt))) (define (pop b) (display "Boom! ") (display (* (car b) (cdr b))) (newline))) (library (party) ;; Total exports: ;; make, push, push!, make-party, pop! (export (rename (balloon:make make) (balloon:push push)) push! make-party (rename (party-pop! pop!))) (import (rnrs) (only (stack) make push! pop!) ; not empty! (prefix (balloons) balloon:)) ;; Creates a party as a stack of balloons, ;; starting with two balloons (define (make-party) (let ([s (make)]) ; from stack (push! s (balloon:make 10 10)) (push! s (balloon:make 12 9)) s)) (define (party-pop! p) (balloon:pop (pop! p)))) (library (main) (export) (import (rnrs) (party)) (define p (make-party)) (pop! p) ; displays "Boom! 108" (push! p (push (make 5 5) 1)) (pop! p)) ; displays "Boom! 24"
マクロとフェーズの例:
(library (my-helpers id-stuff) (export find-dup) (import (rnrs)) (define (find-dup l) (and (pair? l) (let loop ((rest (cdr l))) (cond [(null? rest) (find-dup (cdr l))] [(bound-identifier=? (car l) (car rest)) (car rest)] [else (loop (cdr rest))]))))) (library (my-helpers values-stuff) (export mvlet) (import (rnrs) (for (my-helpers id-stuff) expand)) (define-syntax mvlet (lambda (stx) (syntax-case stx () [( [(id ...) expr] body0 body ...) (not (find-dup (syntax (id ...)))) (syntax (call-with-values (lambda () expr) (lambda (id ...) body0 body ...)))])))) (library (let-div) (export let-div) (import (rnrs) (my-helpers values-stuff) (rnrs r5rs)) (define (quotient+remainder n d) (let ([q (quotient n d)]) (values q (- n (* q d))))) (define-syntax let-div (syntax-rules () [( n d (q r) body0 body ...) (mvlet [(q r) (quotient+remainder n d)] body0 body ...)])))