reduce ( ... seq identity quot: ( ... prev elt -- ... next ) -- ... result )
Factor handbook » The language » Collections » Sequence operations » Sequence combinators

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Vocabulary
sequences

Inputs

seq	a sequence
identity	an object
quot	a quotation with stack effect ( ... prev elt -- ... next )

Outputs

result

the final result

Word description
Combines successive elements of the sequence using a binary operation, and outputs the final result. On the first iteration, the two inputs to the quotation are identity, and the first element of the sequence. On successive iterations, the first input is the result of the previous iteration, and the second input is the corresponding element of the sequence.

Examples

USING: math prettyprint sequences ; { 1 5 3 } 0 [ + ] reduce .
9

Definition

USING: kernel ;

IN: sequences

: reduce
    ( ... seq identity quot: ( ... prev elt -- ... next ) -- ... result )
    swapd each ; inline