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beautiful-racket/beautiful-racket-demo/basic-demo-2/expr.rkt

24 lines
597 B
Racket

#lang br
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(provide b-expr b-sum b-product b-neg b-expt)
(define (b-expr expr)
(if (integer? expr) (inexact->exact expr) expr))
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(define-macro-cases b-sum
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[(_ VAL) #'VAL]
[(_ LEFT "+" RIGHT) #'(+ LEFT RIGHT)]
[(_ LEFT "-" RIGHT) #'(- LEFT RIGHT)])
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(define-macro-cases b-product
[(_ VAL) #'VAL]
[(_ LEFT "*" RIGHT) #'(* LEFT RIGHT)]
[(_ LEFT "/" RIGHT) #'(/ LEFT RIGHT 1.0)]
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[(_ LEFT "mod" RIGHT) #'(modulo LEFT RIGHT)])
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(define-macro-cases b-neg
[(_ VAL) #'VAL]
[(_ "-" VAL) #'(- VAL)])
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(define-macro-cases b-expt
[(_ VAL) #'VAL]
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[(_ LEFT "^" RIGHT) #'(expt LEFT RIGHT)])