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44 lines
1.2 KiB
Racket
44 lines
1.2 KiB
Racket
#lang br
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(require "line.rkt")
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(provide b-expr b-sum b-product b-neg b-expt b-def b-func)
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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-macro (b-def FUNC-ID VAR-ID ... EXPR)
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(syntax-local-lift-expression
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#'(set! FUNC-ID (λ (VAR-ID ...) EXPR))))
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(define-macro (b-func FUNC-ID ARG ...)
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#'(if (procedure? FUNC-ID)
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(let ([result (FUNC-ID ARG ...)])
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(cond
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[(number? result) (b-expr result)]
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[(string? result) result]
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[(boolean? result) (if result 1 0)]
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[else
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(raise-line-error
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(format "unknown data type: ~v" result))]))
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(raise-line-error
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(format "expected ~a to be a function, got ~v"
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'FUNC-ID FUNC-ID))))
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