: ?set-nth ( elt n seq -- )
2dup bounds-check? [ set-nth-unsafe ] [ 3drop ] if ; inline
+: maybe-nth ( i/f seq -- elt/f )
+ over [ nth ] [ 2drop f ] if ; inline
+
: ?first ( seq -- elt/f ) 0 swap ?nth ; inline
: ?second ( seq -- elt/f ) 1 swap ?nth ; inline
: ?last ( seq -- elt/f )
: length-operator ( seq quot -- n quot' )
[ length-iterator ] dip compose ; inline
+: length-operator-last ( seq quot -- n quot' )
+ length-operator [ 1 - ] dip ; inline
+
: sequence-operator-from ( seq quot i -- i n quot' )
-rot length-operator ; inline
+: sequence-operator-last-from ( seq quot i -- n quot' )
+ -rot length-operator-last nip ; inline
+
: collect ( n quot into -- )
[ [ keep ] dip set-nth-unsafe ] 2curry each-integer ; inline
: (3each) ( seq1 seq2 seq3 quot -- n quot' )
[ setup-3each ] dip compose ; inline
-: finish-find ( i seq -- i elt )
- over [ dupd nth-unsafe ] [ drop f ] if ; inline
-
-: (find) ( seq quot quot' -- i elt )
- pick [ [ length-operator ] dip call ] dip finish-find ; inline
-
-: (find-from) ( n seq quot quot' -- i elt )
- [ 2dup bounds-check? ] 2dip
- '[ _ _ (find) ] [ 2drop f f ] if ; inline
+: element/index ( i/f seq -- elt/f i/f )
+ [ maybe-nth ] [ drop ] 2bi ; inline
-: (find-index) ( seq quot quot' -- i elt )
- pick [ [ sequence-index-operator ] dip call ] dip finish-find ; inline
-
-: (find-index-from) ( n seq quot quot' -- i elt )
- [ 2dup bounds-check? ] 2dip
- '[ _ _ (find-index) ] [ 2drop f f ] if ; inline
+: index/element ( i/f seq -- elt/f i/f )
+ [ drop ] [ maybe-nth ] 2bi ; inline
: (accumulate) ( seq identity quot -- identity seq quot' )
swapd [ keepd ] curry ; inline
: 3map ( ... seq1 seq2 seq3 quot: ( ... elt1 elt2 elt3 -- ... newelt ) -- ... newseq )
pickd swap 3map-as ; inline
+: bounds-check-find ( n seq quot -- elt i )
+ 2over bounds-check? [ call ] [ 3drop f f ] if ; inline
+
: find-from ( ... n seq quot: ( ... elt -- ... ? ) -- ... i elt )
- [ find-integer-from ] (find-from) ; inline
+ '[
+ _ [ rot sequence-operator-from find-integer-from ] keepd
+ index/element
+ ] bounds-check-find ; inline
: find ( ... seq quot: ( ... elt -- ... ? ) -- ... i elt )
- [ find-integer ] (find) ; inline
+ [ 0 ] 2dip find-from ; inline
: find-last-from ( ... n seq quot: ( ... elt -- ... ? ) -- ... i elt )
- [ nip find-last-integer ] (find-from) ; inline
+ '[
+ _ [ rot sequence-operator-last-from find-last-integer ] keepd
+ index/element
+ ] bounds-check-find ; inline
: find-last ( ... seq quot: ( ... elt -- ... ? ) -- ... i elt )
- [ [ 1 - ] dip find-last-integer ] (find) ; inline
+ [ [ length 1 - ] keep ] dip find-last-from ; inline
: find-index-from ( ... n seq quot: ( ... elt i -- ... ? ) -- ... i elt )
- [ find-integer-from ] (find-index-from) ; inline
+ '[
+ _ [ sequence-index-operator find-integer-from ] keepd
+ index/element
+ ] bounds-check-find ; inline
: find-index ( ... seq quot: ( ... elt i -- ... ? ) -- ... i elt )
- [ find-integer ] (find-index) ; inline
+ [ 0 ] 2dip find-index-from ; inline
: all? ( ... seq quot: ( ... elt -- ... ? ) -- ... ? )
sequence-operator all-integers-from? ; inline