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beautiful-racket/beautiful-racket-demo/funstacker-demo/funstacker.rkt

28 lines
854 B
Racket

#lang br/quicklang
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(define (read-syntax path port)
(define args (port->lines port))
(define arg-datums (format-datums '~a args))
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(define module-datum `(module stacker-mod "funstacker.rkt"
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(handle-args ,@arg-datums)))
(datum->syntax #f module-datum))
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(provide read-syntax)
(define-macro (funstacker-module-begin HANDLE-ARGS-EXPR)
#'(#%module-begin
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(display (first HANDLE-ARGS-EXPR))))
(provide (rename-out [funstacker-module-begin #%module-begin]))
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(define (handle-args . args)
(for/fold ([stack-acc empty])
([arg (filter-not void? args)])
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(cond
[(number? arg) (cons arg stack-acc)]
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[(or (equal? * arg) (equal? + arg))
(define op-result
(arg (first stack-acc) (second stack-acc)))
(cons op-result (drop stack-acc 2))])))
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(provide handle-args)
(provide + *)