28 lines
826 B
Scheme
28 lines
826 B
Scheme
(define-library
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(arvyy mustache lookup)
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(import (scheme base))
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(export
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compose-lookups
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alist-lookup)
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(begin
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(define (compose-lookups . lookups)
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(lambda (obj name found not-found)
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(let loop ((lookups lookups))
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(if (null? lookups)
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(not-found)
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(let ((l (car lookups)))
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(l obj name found (lambda ()
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(loop (cdr lookups)))))))))
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(define (alist-lookup obj name found not-found)
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(define key (string->symbol name))
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(define alist? (and (list? obj)
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(or (null? obj)
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(pair? (car obj)))))
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(if alist?
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(cond
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((assoc key obj) => (lambda (pair) (found (cdr pair))))
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(else (not-found)))
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(not-found)))))
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