npick ( n -- quot )
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Vocabulary
generalizations

Inputs

n	an integer

Outputs
None

Word description
A generalization of dup, over and pick that can work for any stack depth. The nth item down the stack will be copied and placed on the top of the stack.

Examples

USING: kernel generalizations prettyprint sequences.generalizations ; 1 2 3 4 4 npick 5 narray .
{ 1 2 3 4 1 }

Some core words expressed in terms of npick:

dup	1 npick
over	2 npick
pick	3 npick

Definition

USING: combinators kernel math ;

IN: generalizations

MACRO: npick ( n -- quot )
    {
        { [ dup 0 <= ] [ positive-number-expected ] }
        { [ dup 1 = ] [ drop [ dup ] ] }
        [ 1 - [ dup ] [ [ dip swap ] curry ] swapd times ]
    } cond ;