55 lines
1.0 KiB
Plaintext
55 lines
1.0 KiB
Plaintext
(define (make-counter) (let ((var 0)) (lambda () (set! var (+ 1 var)))))
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(define counter1 (make-counter))
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(assert (= (counter1) 1))
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(define counter2 (make-counter))
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(assert (= (counter2) 1))
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(assert (= (counter2) 2))
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(assert (= (counter1) 2))
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(assert (= (counter1) 3))
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(assert (= (counter2) 3))
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(assert (= (counter2) 4))
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(assert (= (counter2) 5))
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(assert (= (counter1) 4))
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(assert (= (counter1) 5))
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(define (g) (define x 0) (lambda () (define temp x) (mutate x (+ x 1)) temp))
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(define (make-key-counter) ((lambda (:var) (lambda () (mutate var (+ 1 var)) var)) :var 0))
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(define key-counter1 (make-key-counter))
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(assert (= (key-counter1) 1))
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(define key-counter2 (make-key-counter))
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(assert (= (key-counter2) 1))
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(assert (= (key-counter2) 2))
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(assert (= (key-counter1) 2))
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(assert (= (key-counter1) 3))
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(assert (= (key-counter2) 3))
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(assert (= (key-counter2) 4))
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(assert (= (key-counter2) 5))
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(assert (= (key-counter1) 4))
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(assert (= (key-counter1) 5))
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