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16 lines
363 B
Racket
16 lines
363 B
Racket
#lang br
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(require "goto.rkt" "line.rkt")
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(provide b-gosub b-return)
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(define return-stack empty)
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(define (b-gosub num-expr)
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(let/cc return-cc
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(push! return-stack return-cc)
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(b-goto num-expr)))
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(define (b-return)
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(unless (pair? return-stack)
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(raise-line-error "return without gosub"))
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(define top-return-k (pop! return-stack))
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(top-return-k)) |