46 lines
1.2 KiB
Factor
46 lines
1.2 KiB
Factor
! Copyright (C) 2004 Chris Double.
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! See http://factorcode.org/license.txt for BSD license.
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!
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! Updated by Matthew Willis, July 2006
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! Updated by Chris Double, September 2006
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USING: arrays kernel sequences math vectors arrays namespaces
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quotations parser effects inference words ;
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IN: promises
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TUPLE: promise quot forced? value ;
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: promise ( quot -- promise )
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f f \ promise construct-boa ;
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: promise-with ( value quot -- promise )
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curry promise ;
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: promise-with2 ( value1 value2 quot -- promise )
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2curry promise ;
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: force ( promise -- value )
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#! Force the given promise leaving the value of calling the
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#! promises quotation on the stack. Re-forcing the promise
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#! will return the same value and not recall the quotation.
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dup promise-forced? [
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dup promise-quot call over set-promise-value
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t over set-promise-forced?
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] unless
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promise-value ;
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: stack-effect-in ( quot word -- n )
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stack-effect [ ] [ infer ] ?if effect-in length ;
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: make-lazy-quot ( word quot -- quot )
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[
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dup ,
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swap stack-effect-in \ curry <repetition> %
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\ promise ,
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] [ ] make ;
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: LAZY:
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CREATE dup reset-generic
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dup parse-definition
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make-lazy-quot define-compound ; parsing
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