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- ;;; ps-utils --- Utilities for Pre-Scheme
- (define-syntax when
- (syntax-rules ()
- ((_ condition consequent ...)
- (if condition
- (begin consequent ...)))))
- (define-syntax unless
- (syntax-rules ()
- ((_ condition antecedent ...)
- (if (not condition)
- (begin antecedent ...)))))
- (define-syntax define-wrapper-type
- (lambda (exp rename compare)
- (define (symbol-append . args)
- (string->symbol
- (apply string-append (map (lambda (s)
- (if (string? s) s (symbol->string s)))
- args))))
- (let* ((name (cadr exp))
- (type-id (symbol-append ":" name))
- (constructor (rename (symbol-append "make-" name)))
- (%begin (rename 'begin))
- (%define-record-type (rename 'define-record-type))
- (%define-external (rename 'define-external)))
- `(,%define-record-type ,name ,type-id
- (,constructor)))))
- (define (zero? n) (= n 0))
- (define (one? n) (= n 1))
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