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Useful Scheme macros I keep rewriting for every project
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(define-syntax define-syntax-rule | |
(syntax-rules () | |
((_ (name args ...) body) | |
(define-syntax name | |
(syntax-rules () | |
((name args ...) body)))))) | |
(define-syntax-rule (do-times n . body) | |
(do ((i n (sub1 i))) | |
((< i 1)) | |
. body)) | |
(define-syntax-rule (until condition . body) | |
(do () (condition) . body)) | |
(define-syntax-rule (forever . body) | |
(until #f . body)) | |
(define-syntax-rule (if-let (value condition) yes no) | |
(let ((value condition)) | |
(if value yes no))) | |
(define-syntax-rule (when-let (value condition) . body) | |
(let ((value condition)) | |
(when value . body))) | |
(define-syntax-rule (if-not condition yes no) | |
(if condition no yes)) | |
(define-syntax-rule (update! x f) | |
(set! x (f x))) | |
(define-syntax-rule (increment! x) | |
(update! x add1)) | |
(define-syntax-rule (decrement! x) | |
(update! x sub1)) | |
(define-syntax-rule (thunk body body* ...) | |
(lambda () body body* ...)) | |
(define-syntax-rule (thunk* body body* ...) | |
(lambda ignored body body* ...)) | |
(define-syntax -> | |
(syntax-rules () | |
((_ x) | |
x) | |
((_ x (f arg ...) rest ...) | |
(-> (f x arg ...) rest ...)) | |
((_ x f rest ...) | |
(-> (f x) rest ...)))) | |
(define-syntax ->> | |
(syntax-rules () | |
((_ x) | |
x) | |
((_ x (f arg ...) rest ...) | |
(->> (f arg ... x) rest ...)) | |
((_ x f rest ...) | |
(->> (f x) rest ...)))) | |
(define-syntax do-to | |
(syntax-rules () | |
((_ x) | |
x) | |
((_ x (f arg ...) rest ...) | |
(begin | |
(f arg ... x) | |
(do-to x rest ...))) | |
((_ x f rest ...) | |
(do-to x (f) rest ...)))) |
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