ikarus/lib/libcafe.ss

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(let ()
(define with-error-handler
(lambda (p thunk)
(let ([old-error-handler (error-handler)])
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(dynamic-wind
(lambda ()
(error-handler
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(lambda args
(error-handler old-error-handler)
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(apply p args)
(apply error args))))
thunk
(lambda ()
(error-handler old-error-handler))))))
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(define eval-depth 0)
(define display-prompt
(lambda (i)
(if (fx= i eval-depth)
(display " " (console-output-port))
(begin
(display ">" (console-output-port))
(display-prompt (fx+ i 1))))))
(define wait
(lambda (eval escape-k)
(call/cc
(lambda (k)
(with-error-handler
(lambda args
(reset-input-port! (console-input-port))
(apply print-error args)
(k (void)))
(lambda ()
(display-prompt 0)
(let ([x (read (console-input-port))])
(cond
[(eof-object? x)
(newline (console-output-port))
(escape-k (void))]
[else
(call-with-values
(lambda () (eval x))
(lambda v*
(unless (andmap (lambda (v) (eq? v (void))) v*)
(for-each
(lambda (v)
(write v (console-output-port))
(newline (console-output-port)))
v*))))]))))))
(wait eval escape-k)))
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(define new-cafe
(lambda (eval)
(dynamic-wind
(lambda () (set! eval-depth (fxadd1 eval-depth)))
(lambda ()
(call/cc
(lambda (k)
(wait eval k))))
(lambda () (set! eval-depth (fxsub1 eval-depth))))))
(primitive-set! 'new-cafe
(case-lambda
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[() (new-cafe eval)]
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[(p)
(unless (procedure? p)
(error 'new-cafe "~s is not a procedure" p))
(new-cafe p)]))
)
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