reduce ( ... seq identity quot: ( ... prev elt -- ... next ) -- ... result )

Vocabulary
sequences

Inputs and outputs

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

Prev:	each-index ( ... seq quot: ( ... elt index -- ... ) -- ... )
Next:	interleave ( ... seq between quot: ( ... elt -- ... ) -- ... )