backtrack: some cleanup.
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@ -1,8 +1,8 @@
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! Copyright (C) 2008 William Schlieper
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! See http://factorcode.org/license.txt for BSD license.
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USING: kernel continuations combinators sequences quotations arrays namespaces
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fry summary assocs math math.order macros ;
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USING: assocs combinators continuations fry kernel macros math
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namespaces quotations sequences summary ;
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IN: backtrack
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@ -13,16 +13,18 @@ ERROR: amb-failure ;
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M: amb-failure summary drop "Backtracking failure" ;
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: fail ( -- )
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failure get [ continue ]
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[ amb-failure ] if* ;
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failure get [ continue ] [ amb-failure ] if* ;
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: require ( ? -- )
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[ fail ] unless ;
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MACRO: checkpoint ( quot -- quot' )
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'[ failure get _
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'[ '[ failure set _ continue ] callcc0
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_ failure set @ ] callcc0 ] ;
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'[
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failure get _ '[
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'[ failure set _ continue ] callcc0
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_ failure set @
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] callcc0
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] ;
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: number-from ( from -- from+n )
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[ 1 + number-from ] checkpoint ;
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@ -43,10 +45,11 @@ MACRO: checkpoint ( quot -- quot' )
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length 1 - 0 number-from-to nip ;
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MACRO: unsafe-amb ( seq -- quot )
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dup length 1 =
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[ first 1quotation ]
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[ [ first ] [ rest ] bi
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'[ _ [ drop _ unsafe-amb ] checkpoint ] ] if ;
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dup length 1 = [
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first 1quotation
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] [
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unclip swap '[ _ [ drop _ unsafe-amb ] checkpoint ]
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] if ;
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PRIVATE>
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@ -54,8 +57,7 @@ PRIVATE>
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[ amb-integer ] [ nth ] bi ;
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: amb ( seq -- elt )
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[ fail f ]
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[ unsafe-amb ] if-empty ; inline
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[ fail f ] [ unsafe-amb ] if-empty ; inline
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MACRO: amb-execute ( seq -- quot )
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[ length 1 - ] [ <enum> [ 1quotation ] assoc-map ] bi
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