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30 lines
709 B
Racket
30 lines
709 B
Racket
#lang br
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(provide b-expr b-sum b-product b-neg b-expt)
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(define (b-expr expr)
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(if (integer? expr) (inexact->exact expr) expr))
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(define-macro-cases b-sum
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[(_ VAL) #'VAL]
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[(_ LEFT "+" RIGHT) #'(+ LEFT RIGHT)]
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[(_ LEFT "-" RIGHT) #'(- LEFT RIGHT)])
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(define-macro-cases b-product
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[(_ VAL) #'VAL]
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[(_ LEFT "*" RIGHT) #'(* LEFT RIGHT)]
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[(_ 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
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[(_ VAL) #'VAL]
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[(_ "-" VAL) #'(- VAL)])
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(define-macro-cases b-expt
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[(_ VAL) #'VAL]
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[(_ LEFT "^" RIGHT) #'(expt LEFT RIGHT)])
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(define (b-not expr) (if (zero? expr) 1 0))
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(define-macro (b-def ID VAR EXPR)
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#'(set! ID (λ (VAR) EXPR)))
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