-USING: accessors arrays assocs combinators fry generalizations
-grouping growable kernel locals make math math.order math.ranges
-sequences sequences.deep sequences.private sorting splitting
-vectors ;
+USING: accessors arrays assocs combinators generalizations
+grouping growable heaps kernel math math.order ranges sequences
+sequences.private shuffle sorting splitting vectors ;
IN: sequences.extras
-: reduce1 ( seq quot -- result ) [ unclip ] dip reduce ; inline
-
-:: reduce-r ( seq identity quot: ( obj1 obj2 -- obj ) -- result )
- seq [ identity ] [
- unclip [ identity quot reduce-r ] [ quot call ] bi*
- ] if-empty ; inline recursive
-
-! Quot must have static stack effect, unlike "reduce"
-:: reduce* ( seq identity quot: ( prev elt -- next ) -- result )
- seq [ identity ] [
- unclip identity swap quot call( prev elt -- next )
- quot reduce*
- ] if-empty ; inline recursive
-
-:: combos ( list1 list2 -- result )
- list2 [ [ 2array ] curry list1 swap map ] map concat ;
-
-: find-all ( seq quot: ( elt -- ? ) -- elts )
- [ [ length iota ] keep ] dip
- [ dupd call( a -- ? ) [ 2array ] [ 2drop f ] if ] curry
- 2map sift ; inline
+: find-all ( ... seq quot: ( ... elt -- ... ? ) -- ... elts )
+ [ <enumerated> ] dip '[ nip @ ] assoc-filter ; inline
: reduce-from ( ... seq identity quot: ( ... prev elt -- ... next ) i -- ... result )
[ swap ] 2dip each-from ; inline
[ length '[ 0 _ clamp ] bi@ ] keep subseq ;
: all-subseqs ( seq -- seqs )
- dup length [1,b] [ clump ] with map concat ;
-
-:: each-subseq ( ... seq quot: ( ... x -- ... ) -- ... )
- seq length :> len
- len [0,b] [
- :> from
- from len (a,b] [
- :> to
- from to seq subseq quot call
- ] each
- ] each ; inline
+ dup length [1..b] [ clump ] with map concat ;
-: subseq-as ( from to seq exemplar -- subseq )
- [ check-slice subseq>copy (copy) ] dip like ;
+: each-subseq ( ... seq quot: ( ... subseq -- ... ) -- ... )
+ [ dup length [ [0..b] ] [ ] bi ] dip '[
+ dup _ (a..b] [ rot [ subseq _ call ] keep ] with each
+ ] each drop ; inline
: map-like ( seq exemplar -- seq' )
'[ _ like ] map ; inline
-: filter-all-subseqs-range ( ... seq range quot: ( ... x -- ... ) -- seq )
+: filter-all-subseqs-range ( ... seq range quot: ( ... subseq -- ... ? ) -- seq )
[
'[ <clumps> _ filter ] with map concat
- ] 3keep 2drop map-like ; inline
+ ] keepdd map-like ; inline
-: filter-all-subseqs ( ... seq quot: ( ... x -- ... ) -- seq )
- [ dup length [1,b] ] dip filter-all-subseqs-range ; inline
+: filter-all-subseqs ( ... seq quot: ( ... subseq -- ... ? ) -- seq )
+ [ dup length [1..b] ] dip filter-all-subseqs-range ; inline
:: longest-subseq ( seq1 seq2 -- subseq )
seq1 length :> len1
0 :> n!
0 :> end!
len1 1 + [ len2 1 + 0 <array> ] replicate :> table
- len1 [1,b] [| x |
- len2 [1,b] [| y |
+ len1 [1..b] [| x |
+ len2 [1..b] [| y |
x 1 - seq1 nth-unsafe
y 1 - seq2 nth-unsafe = [
y 1 - x 1 - table nth-unsafe nth-unsafe 1 + :> len
: pad-longest ( seq1 seq2 elt -- seq1 seq2 )
[ 2dup max-length ] dip [ pad-tail ] 2curry bi@ ;
+: pad-center ( seq n elt -- padded )
+ swap pick length [-] [ drop ] [
+ [ 2/ ] [ over - ] bi rot '[ _ <repetition> ] bi@
+ pick surround-as
+ ] if-zero ;
+
: change-nths ( ... indices seq quot: ( ... elt -- ... elt' ) -- ... )
[ change-nth ] 2curry each ; inline
: push-if-index ( ..a elt i quot: ( ..a elt i -- ..b ? ) accum -- ..b )
- [ 2keep drop ] dip rot [ push ] [ 2drop ] if ; inline
+ [ keepd ] dip rot [ push ] [ 2drop ] if ; inline
: push-if* ( ..a elt quot: ( ..a elt -- ..b obj/f ) accum -- ..b )
[ call ] dip [ push ] [ drop ] if* ; inline
<PRIVATE
-: (index-selector-for) ( quot length exampler -- selector accum )
+: (index-selector-as) ( quot length exampler -- selector accum )
new-resizable [ [ push-if-index ] 2curry ] keep ; inline
-: (selector-for*) ( quot length exemplar -- selector accum )
+: (selector-as*) ( quot length exemplar -- selector accum )
new-resizable [ [ push-if* ] 2curry ] keep ; inline
PRIVATE>
-: index-selector-for ( quot exemplar -- selector accum )
- [ length ] keep (index-selector-for) ; inline
+: index-selector-as ( quot exemplar -- selector accum )
+ [ length ] keep (index-selector-as) ; inline
: index-selector ( quot -- selector accum )
- V{ } index-selector-for ; inline
+ V{ } index-selector-as ; inline
-: selector-for* ( quot exemplar -- selector accum )
- [ length ] keep (selector-for*) ; inline
+: selector-as* ( quot exemplar -- selector accum )
+ [ length ] keep (selector-as*) ; inline
-: selector* ( quot -- selector accum ) V{ } selector-for* ; inline
+: selector* ( quot -- selector accum ) V{ } selector-as* ; inline
: filter-index-as ( ... seq quot: ( ... elt i -- ... ? ) exemplar -- ... seq' )
- pick length over [ (index-selector-for) [ each-index ] dip ] 2curry dip like ; inline
+ pick length over [ (index-selector-as) [ each-index ] dip ] 2curry dip like ; inline
: filter-index ( ... seq quot: ( ... elt i -- ... ? ) -- ... seq' )
over filter-index-as ; inline
: even-indices ( seq -- seq' )
[ length 1 + 2/ ] keep [
[ [ 2 * ] dip nth-unsafe ] curry
- ] keep map-integers ;
+ ] keep map-integers-as ;
: odd-indices ( seq -- seq' )
[ length 2/ ] keep [
[ [ 2 * 1 + ] dip nth-unsafe ] curry
- ] keep map-integers ;
+ ] keep map-integers-as ;
: compact ( ... seq quot: ( ... elt -- ... ? ) elt -- ... seq' )
[ split-when harvest ] dip join ; inline
[ seq <slice> ] keep len or swap
] produce nip ; inline
-: cut-slice* ( seq n -- before after )
- [ head-slice* ] [ tail-slice* ] 2bi ;
-
-: ?<slice> ( from to/f sequence -- slice )
- over [ nip [ length ] [ ] bi ] unless <slice> ; inline
+: ?<slice> ( from/f to/f sequence -- slice )
+ [ [ 0 ] unless* ] 2dip
+ over [ nip [ length ] [ ] bi ] unless
+ <slice> ; inline
: sequence>slice ( sequence -- slice )
[ drop 0 ] [ length ] [ ] tri <slice> ; inline
over length mod dup 0 >= [ cut ] [ abs cut* ] if prepend ;
ERROR: underlying-mismatch slice1 slice2 ;
+
: ensure-same-underlying ( slice1 slice2 -- slice1 slice2 )
2dup [ seq>> ] bi@ eq? [ underlying-mismatch ] unless ;
[ [ to>> ] bi@ max ]
[ drop seq>> ] 2tri <slice> ;
+: ?span-slices ( slice1/f slice2/f -- slice )
+ 2dup and [ span-slices ] [ or ] if ;
+
:: rotate! ( seq n -- )
seq length :> len
n len mod dup 0 < [ len + ] when seq bounds-check drop 0 over
] until 3drop ;
: all-rotations ( seq -- seq' )
- dup length iota [ rotate ] with map ;
+ dup length <iota> [ rotate ] with map ;
<PRIVATE
: map-concat ( ... seq quot: ( ... elt -- ... newelt ) -- ... newseq )
over empty? [ 2drop { } ] [
- [ [ first ] dip call ] 2keep rot dup [
- >resizable [ [ push-all ] curry compose ] keep
- [ 1 ] 3dip [ setup-each (each-integer) ] dip
- ] curry dip like
+ [ [ first ] dip call ] 2keep rot [
+ >resizable [ '[ @ _ push-all ] 1 each-from ] keep
+ ] keep like
] if ; inline
: map-filter-as ( ... seq map-quot: ( ... elt -- ... newelt ) filter-quot: ( ... newelt -- ... ? ) exemplar -- ... subseq )
- [ pick ] dip swap length over
- [ (selector-for) [ compose each ] dip ] 2curry dip like ; inline
+ reach length over
+ [ (selector-as) [ compose each ] dip ] 2curry dip like ; inline
: map-filter ( ... seq map-quot: ( ... elt -- ... newelt ) filter-quot: ( ... newelt -- ... ? ) -- ... subseq )
pick map-filter-as ; inline
: map-harvest ( ... seq quot: ( ... elt -- ... newelt ) -- ... newseq )
[ empty? not ] map-filter ; inline
+: (each-integer-with-previous) ( ... prev i n quot: ( ... i -- ... ) -- ... )
+ 2over < [
+ [ nip call ] 4keep nipdd
+ [ 1 + ] 2dip (each-integer-with-previous)
+ ] [
+ 4drop
+ ] if ; inline recursive
+
+: each-integer-with-previous ( ... n quot: ( ... i -- ... ) -- ... )
+ [ f 0 ] 2dip (each-integer-with-previous) ; inline
+
+: (collect-with-previous) ( quot into -- quot' )
+ [ [ keep ] dip [ set-nth-unsafe ] keepdd ] 2curry ; inline
+
+: collect-with-previous ( n quot into -- )
+ (collect-with-previous) each-integer-with-previous ; inline
+
+: map-integers-with ( ... len quot: ( ... prev i -- ... elt ) exemplar -- ... newseq )
+ overd [ [ collect-with-previous ] keep ] new-like ; inline
+
+: map-with-previous-as ( ... seq quot: ( ... elt prev/f -- ... newelt ) exemplar -- ... newseq )
+ [ length-operator ] dip map-integers-with ; inline
+
+: map-with-previous ( ... seq quot: ( ... elt prev/f -- ... newelt ) -- ... newseq )
+ over map-with-previous-as ; inline
+
<PRIVATE
: (setup-each-from) ( i seq -- n quot )
PRIVATE>
: map-from-as ( ... seq quot: ( ... elt -- ... newelt ) i exemplar -- ... newseq )
- [ -rot setup-each-from ] dip map-integers ; inline
+ [ -rot setup-each-from ] dip map-integers-as ; inline
: map-from ( ... seq quot: ( ... elt -- ... newelt ) i -- ... newseq )
pick map-from-as ; inline
+: map-if ( ... seq if-quot: ( ... elt -- ... ? ) map-quot: ( ... elt -- ... newelt ) -- ... newseq )
+ '[ dup @ _ when ] map ; inline
+
<PRIVATE
: push-map-if ( ..a elt filter-quot: ( ..a elt -- ..b ? ) map-quot: ( ..a elt -- ..b newelt ) accum -- ..b )
PRIVATE>
: filter-map-as ( ... seq filter-quot: ( ... elt -- ... ? ) map-quot: ( ... elt -- ... newelt ) exemplar -- ... newseq )
- [ pick ] dip swap length over
+ reach length over
[ (filter-mapper-for) [ each ] dip ] 2curry dip like ; inline
: filter-map ( ... seq filter-quot: ( ... elt -- ... ? ) map-quot: ( ... elt -- ... newelt ) -- ... newseq )
: 2count ( ... seq1 seq2 quot: ( ... elt1 elt2 -- ... ? ) -- ... n )
[ 1 0 ? ] compose 2map-sum ; inline
+: 3each-from
+ ( ... seq1 seq2 seq3 quot: ( ... elt1 elt2 elt3 -- ... ) i -- ... )
+ [ (3each) ] dip -rot each-integer-from ; inline
+
+: 3map-reduce
+ ( ..a seq1 seq2 seq3 map-quot: ( ..a elt1 elt2 elt3 -- ..b intermediate ) reduce-quot: ( ..b prev intermediate -- ..a next ) -- ..a result )
+ [ [ [ [ first ] tri@ ] 3keep ] dip [ 3dip ] keep ] dip compose 1 3each-from ; inline
+
: round-robin ( seq -- newseq )
[ { } ] [
- [ longest length iota ] keep
+ [ longest length <iota> ] keep
[ [ ?nth ] with map ] curry map concat sift
] if-empty ;
: unsurround ( newseq seq2 seq3 -- seq1 )
[ ?head drop ] [ ?tail drop ] bi* ;
-: none? ( ... seq quot: ( ... elt -- ... ? ) -- ... ? )
- any? not ; inline
+: >string-list ( seq -- seq' )
+ [ "\"" 1surround ] map "," join ;
+
+: with-string-lines ( str quot -- str' )
+ [ string-lines ] dip map "\n" join ; inline
+
+: prepend-lines-with-spaces ( str -- str' )
+ [ " " prepend ] with-string-lines ;
: one? ( ... seq quot: ( ... elt -- ... ? ) -- ... ? )
[ find ] 2keep rot [
] [ 3drop f ] if ; inline
: map-index! ( ... seq quot: ( ... elt index -- ... newelt ) -- ... seq )
- over [ [ (each-index) ] dip collect ] keep ; inline
+ over [ [ sequence-index-operator ] dip collect ] keep ; inline
<PRIVATE
pick [ 2map-into ] keep ; inline
: 2map-index ( ... seq1 seq2 quot: ( ... elt1 elt2 index -- ... newelt ) -- ... newseq )
- pick [ (2each-index) ] dip map-integers ; inline
+ pick [ (2each-index) ] dip map-integers-as ; inline
-TUPLE: evens seq length ;
+TUPLE: evens { seq read-only } ;
-: <evens> ( seq -- evens )
- dup length 1 + 2/ evens boa ; inline
+C: <evens> evens
-M: evens length length>> ; inline
+M: evens length seq>> length 1 + 2/ ; inline
-M: evens nth-unsafe [ 2 * ] [ seq>> nth-unsafe ] bi* ; inline
+M: evens virtual@ [ 2 * ] [ seq>> ] bi* ; inline
-INSTANCE: evens immutable-sequence
+M: evens virtual-exemplar seq>> ; inline
-TUPLE: odds seq length ;
+INSTANCE: evens virtual-sequence
-: <odds> ( seq -- odds )
- dup length 2/ odds boa ; inline
+TUPLE: odds { seq read-only } ;
-M: odds length length>> ; inline
+C: <odds> odds
-M: odds nth-unsafe [ 2 * 1 + ] [ seq>> nth-unsafe ] bi* ; inline
+M: odds length seq>> length 2/ ; inline
-INSTANCE: odds immutable-sequence
+M: odds virtual@ [ 2 * 1 + ] [ seq>> ] bi* ; inline
-: until-empty ( seq quot -- )
- [ dup empty? ] swap until drop ; inline
+M: odds virtual-exemplar seq>> ; inline
-: arg-max ( seq -- n )
- <enum> [ second-unsafe ] supremum-by first ;
+INSTANCE: odds virtual-sequence
-: arg-min ( seq -- n )
- <enum> [ second-unsafe ] infimum-by first ;
+: until-empty ( seq quot -- )
+ [ dup empty? ] swap until drop ; inline
<PRIVATE
: last? ( ... seq quot: ( ... elt -- ... ? ) -- ... ? ) [ last ] dip call ; inline
: nth? ( ... n seq quot: ( ... elt -- ... ? ) -- ... ? ) [ nth ] dip call ; inline
-: loop>sequence ( quot exemplar -- seq )
- [ '[ [ @ [ [ , ] when* ] keep ] loop ] ] dip make ; inline
+: loop>sequence** ( ... quot: ( ... -- ... obj ? ) exemplar -- ... seq )
+ [ ] swap produce-as nip ; inline
+
+: loop>array** ( ... quot: ( ... -- ... obj ? ) -- ... array )
+ { } loop>sequence** ; inline
+
+: loop>sequence* ( ... quot: ( ... -- ... obj ? ) exemplar -- ... seq )
+ [ t ] [ '[ [ _ dip ] [ f f f ] if* ] [ swap ] ] [ produce-as 2nip ] tri* ; inline
+
+: loop>array* ( ... quot: ( ... -- ... obj ? ) -- ... array )
+ { } loop>sequence* ; inline
-: loop>array ( quot -- seq )
+: loop>sequence ( ... quot: ( ... -- ... obj/f ) exemplar -- ... seq )
+ [ [ dup ] compose [ ] ] dip produce-as nip ; inline
+
+: loop>array ( ... quot: ( ... -- ... obj/f ) -- ... array )
{ } loop>sequence ; inline
+: zero-loop>sequence ( ... quot: ( ... n -- ... obj/f ) exemplar -- ... seq )
+ [ 0 ] [ '[ _ keep 1 + swap ] ] [ loop>sequence ] tri* nip ; inline
+
+: zero-loop>array ( quot: ( ..a n -- ..a obj ) -- seq )
+ { } zero-loop>sequence ; inline
+
+: iterate-heap-while ( heap quot1: ( value key -- slurp? ) quot2: ( value key -- obj/f ) -- obj/f loop? )
+ pick heap-empty?
+ [ 3drop f f ]
+ [
+ [ [ heap-peek ] 2dip drop 2keep ]
+ [
+ nip ! ( pop? value key heap quot2 )
+ 5roll [
+ swap heap-pop* call( value key -- obj/f ) t
+ ] [
+ 4drop f f
+ ] if
+ ] 3bi
+ ] if ; inline
+
+: slurp-heap-while-map ( heap quot1: ( value key -- slurp? ) quot2: ( value key -- obj/f ) -- seq )
+ '[ _ _ _ iterate-heap-while ] loop>array* ; inline
+
+: heap>pairs ( heap -- pairs )
+ [ 2drop t ] [ swap 2array ] slurp-heap-while-map ;
+
+: map-zip-swap ( quot: ( x -- y ) -- alist )
+ '[ _ keep ] map>alist ; inline
+
+: ?heap-pop-value>array ( heap -- array )
+ dup heap-empty? [ drop { } ] [ heap-pop drop 1array ] if ;
+
<PRIVATE
: (reverse) ( seq -- newseq )
[ 1 ] 2dip [ dip * ] curry [ swap ] prepose each ; inline
: insert-nth! ( elt n seq -- )
- [ length ] keep ensure swap pick (a,b]
+ [ length ] keep ensure swap pick (a..b]
over '[ [ 1 + ] keep _ move-unsafe ] each
set-nth-unsafe ;
: set-nths-unsafe ( value indices seq -- )
swapd '[ _ swap _ set-nth-unsafe ] each ; inline
-: flatten1 ( obj -- seq )
- [
- [
- dup branch? [
- [ dup branch? [ % ] [ , ] if ] each
- ] [ , ] if
- ]
- ] keep dup branch? [ drop f ] unless make ;
-
<PRIVATE
: (map-find-index) ( seq quot find-quot -- result i elt )
} case ;
: cut-when ( ... seq quot: ( ... elt -- ... ? ) -- ... before after )
- [ find drop ] 2keep drop swap
+ [ find drop ] keepd swap
[ cut ] [ f over like ] if* ; inline
: nth* ( n seq -- elt )
[ length 1 - swap - ] [ nth ] bi ; inline
: each-index-from ( ... seq quot: ( ... elt index -- ... ) i -- ... )
- -rot (each-index) (each-integer) ; inline
+ -rot sequence-index-operator each-integer-from ; inline
<PRIVATE
: infimum-by* ( ... seq quot: ( ... elt -- ... x ) -- ... i elt )
[ before? ] select-by* ; inline
+: arg-max ( seq -- n )
+ [ ] supremum-by* drop ;
+
+: arg-min ( seq -- n )
+ [ ] infimum-by* drop ;
+
+: ?supremum ( seq/f -- elt/f )
+ [ f ] [
+ [ ] [ 2dup and [ max ] [ dupd ? ] if ] map-reduce
+ ] if-empty ;
+
+: ?infimum ( seq/f -- elt/f )
+ [ f ] [
+ [ ] [ 2dup and [ min ] [ dupd ? ] if ] map-reduce
+ ] if-empty ;
+
: change-last ( seq quot -- )
- [ drop length 1 - ] [ change-nth ] 2bi ; inline
+ [ index-of-last ] [ change-nth ] bi* ; inline
: change-last-unsafe ( seq quot -- )
- [ drop length 1 - ] [ change-nth-unsafe ] 2bi ; inline
+ [ index-of-last ] [ change-nth-unsafe ] bi* ; inline
: replicate-into ( ... seq quot: ( ... -- ... newelt ) -- ... )
over [ length ] 2dip '[ _ dip _ set-nth-unsafe ] each-integer ; inline
: count* ( ... seq quot: ( ... elt -- ... ? ) -- ... % )
over [ count ] [ length ] bi* / ; inline
+: sequence-index-operator-last ( n seq quot -- n quot' )
+ [ [ nth-unsafe ] curry [ keep ] curry ] dip compose ; inline
+
+: find-last-index-from ( ... n seq quot: ( ... elt i -- ... ? ) -- ... i elt )
+ '[
+ _ [ sequence-index-operator-last find-last-integer ] keepd
+ index/element
+ ] bounds-check-call ; inline
+
: find-last-index ( ... seq quot: ( ... elt i -- ... ? ) -- ... i elt )
- [ [ 1 - ] dip find-last-integer ] (find-index) ; inline
+ [ index-of-last ] dip find-last-index-from ; inline
: map-find-last-index ( ... seq quot: ( ... elt index -- ... result/f ) -- ... result i elt )
[ find-last-index ] (map-find-index) ; inline
-:: (start-all) ( subseq seq increment -- indices )
+:: (start-all) ( seq subseq increment -- indices )
0
- [ [ subseq seq ] dip start* dup ]
+ [ seq subseq subseq-index-from dup ]
[ [ increment + ] keep ] produce nip ;
-: start-all ( subseq seq -- indices )
- over length (start-all) ; inline
+: start-all ( seq subseq -- indices )
+ dup length (start-all) ; inline
-: start-all* ( subseq seq -- indices )
+: start-all* ( seq subseq -- indices )
1 (start-all) ; inline
-: count-subseq ( subseq seq -- n )
+: count-subseq ( seq subseq -- n )
start-all length ; inline
-: count-subseq* ( subseq seq -- n )
+: count-subseq* ( seq subseq -- n )
start-all* length ; inline
-: map-zip ( quot: ( x -- y ) -- alist )
- '[ _ keep swap ] map>alist ; inline
+: assoc-zip-with ( quot: ( key value -- calc ) -- alist )
+ '[ _ 2keep 2array swap ] assoc-map ; inline
+
+: take-while ( ... seq quot: ( ... elt -- ... ? ) -- head-slice )
+ [ '[ @ not ] find drop ] keepd swap
+ [ dup length ] unless* head-slice ; inline
+
+: drop-while ( ... seq quot: ( ... elt -- ... ? ) -- tail-slice )
+ [ '[ @ not ] find drop ] keepd swap
+ [ dup length ] unless* tail-slice ; inline
+
+: count-head ( seq quot -- n )
+ [ not ] compose [ find drop ] keepd length or ; inline
+
+: count-tail ( seq quot -- n )
+ [ not ] compose [ find-last drop ] keepd
+ length swap [ - 1 - ] when* ; inline
+
+:: shorten* ( vector n -- seq )
+ vector n tail
+ n vector shorten ;
+
+:: interleaved-as ( seq glue exemplar -- newseq )
+ seq length dup 1 - + 0 max exemplar new-sequence :> newseq
+ seq [ 2 * newseq set-nth-unsafe ] each-index
+ seq length 1 - [ 2 * 1 + glue swap newseq set-nth-unsafe ] each-integer
+ newseq ;
+
+: interleaved ( seq glue -- newseq )
+ over interleaved-as ;
+
+: extract! ( ... seq quot: ( ... elt -- ... ? ) -- ... seq )
+ [ dup ] compose over [ length ] keep new-resizable
+ [ [ push-if ] 2curry reject! ] keep swap like ; inline
+
+: find-pred-loop ( ... i n seq quot: ( ... elt -- ... calc ? ) -- ... calc/f i/f elt/f )
+ 2pick < [
+ [ nipd call ] 4keep
+ 3 7 0 nrotated
+ [ [ 3drop ] 2dip rot ]
+ [ 2drop [ 1 + ] 3dip find-pred-loop ] if
+ ] [
+ 4drop f f f
+ ] if ; inline recursive
+
+: find-pred ( ... seq quot: ( ... elt -- ... calc ) pred: ( ... calc -- ... ? ) -- ... calc/f i/f elt/f )
+ [ 0 ] 3dip
+ [ [ length check-length ] keep ] 2dip
+ '[ nth-unsafe _ keep swap _ keep swap ] find-pred-loop swapd ; inline
+
+! https://en.wikipedia.org/wiki/Maximum_subarray_problem
+! Kadane's algorithm O(n) largest sum in subarray
+: max-subarray-sum ( seq -- sum )
+ [ -1/0. 0 ] dip
+ [ [ + ] keep max [ max ] keep ] each drop ;
+
+TUPLE: step-slice
+ { from integer read-only initial: 0 }
+ { to integer read-only initial: 0 }
+ { seq read-only }
+ { step integer read-only } ;
+
+:: <step-slice> ( from to step seq -- step-slice )
+ step zero? [ "can't be zero" throw ] when
+ seq length :> len
+ step 0 > [
+ from [ 0 ] unless*
+ to [ len ] unless*
+ ] [
+ from [ len ] unless*
+ to [ 0 ] unless*
+ ] if
+ [ dup 0 < [ len + ] when 0 len clamp ] bi@
+ ! FIXME: make this work with steps
+ seq dup slice? [ collapse-slice ] when
+ step step-slice boa ;
+
+M: step-slice virtual-exemplar seq>> ; inline
+
+M: step-slice virtual@
+ [ step>> * ] [ from>> + ] [ seq>> ] tri ; inline
+
+M: step-slice length
+ [ to>> ] [ from>> - ] [ step>> ] tri
+ dup 0 < [ [ neg 0 max ] dip neg ] when /mod
+ zero? [ 1 + ] unless ; inline
+
+INSTANCE: step-slice virtual-sequence
projects / factor.git / blobdiff