23 lines
620 B
Factor
Executable File
23 lines
620 B
Factor
Executable File
! Copyright (C) 2004, 2006 Chris Double, Matthew Willis.
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! See http://factorcode.org/license.txt for BSD license.
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USING: arrays kernel sequences math arrays namespaces
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parser effects generalizations fry words accessors ;
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IN: promises
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TUPLE: promise quot forced? value ;
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: promise ( quot -- promise ) f f \ promise boa ;
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: force ( promise -- value )
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dup forced?>> [
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dup quot>> call( -- value ) >>value
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t >>forced?
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] unless
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value>> ;
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: make-lazy-quot ( quot effect -- quot )
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in>> length '[ _ _ ncurry promise ] ;
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SYNTAX: LAZY:
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(:) [ make-lazy-quot ] [ 2nip ] 3bi define-declared ;
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