27 lines
619 B
Scheme
27 lines
619 B
Scheme
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#!/usr/bin/env scheme-script
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(import (ikarus) (match))
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(define (constant? x)
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(or (number? x) (char? x) (string? x) (boolean? x)))
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(define (ee x)
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(define (ee x env)
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(trace-match foo x
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[,c (guard (constant? c)) c]
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[,x (guard (symbol? x))
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(cond
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((assq x env) => cdr)
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(else (error 'ee "unbound variable" x)))]
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[(let ([,x* ,[v*]] ...) ,b)
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(ee b (append (map cons x* v*) env))]
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[(+ ,[x] ,[y]) (+ x y)]
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[,others (error 'ee "invalid expression" others)]))
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(ee x '()))
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(pretty-print
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(ee '(let ((x 5)) (let ((y (+ x x))) (+ y x)))))
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;(new-cafe ee)
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