2map-reduce ( ..a seq1 seq2 map-quot: ( ..a elt1 elt2 -- ..a intermediate ) reduce-quot: ( ..a prev intermediate -- ..a next ) -- ..a result )
Factor handbook » The language » Collections » Sequence operations » Sequence combinators » Pair-wise sequence combinators

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Vocabulary
sequences

Inputs

seq1	a sequence
seq2	a sequence
map-quot	a quotation with stack effect ( ..a elt1 elt2 -- ..a intermediate )
reduce-quot	a quotation with stack effect ( ..a prev intermediate -- ..a next )

Outputs

result

an object

Word description
Calls map-quot on each pair of elements from seq1 and seq2 and combines the results using reduce-quot in the same manner as reduce, except that there is no identity element, and the sequence must have a length of at least 1.

Errors
Throws an error if the sequence is empty.

Examples

USING: sequences prettyprint math ; { 10 30 50 } { 200 400 600 } [ + ] [ + ] 2map-reduce .
1290

Definition

USING: kernel ;

IN: sequences

: 2map-reduce
    ( ..a seq1 seq2 map-quot: ( ..a elt1 elt2 -- ..a intermediate ) reduce-quot: ( ..a prev intermediate -- ..a next ) -- ..a result )
    [ [ [ [ first ] bi@ ] 2keep ] dip [ 2dip ] keep ] dip
    [ [ [ rot ] ] dip [ dip swap ] curry compose ] dip compose
    1 2each-from ; inline