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#lang racket/base
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(require br/define (for-syntax racket/base syntax/parse))
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(provide (all-defined-out))
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(define-macro (values->list EXPR)
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#'(call-with-values (λ () EXPR) list))
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(define-syntax (push! stx)
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(syntax-parse stx
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[(_ ID:id VAL)
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#'(set! ID (cons VAL ID))]))
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(define-syntax (pop! stx)
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(syntax-parse stx
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[(_ ID:id)
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#'(let ([x (car ID)])
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(set! ID (cdr ID))
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x)]))
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(module+ test
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(require rackunit)
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(check-equal? '(1 2 3) (values->list (values 1 2 3)))
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(check-equal? (let ([xs '(2 3)])
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(push! xs 1)
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xs) '(1 2 3))
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(check-equal? (let ([xs '(1 2 3)])
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(define x (pop! xs))
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(cons x xs)) '(1 2 3)))
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