firstn ( n -- quot )
Generalized sequence words

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Vocabulary
sequences.generalizations

Inputs

n	an integer

Outputs
None

Word description
A generalization of first, first2, first3 and first4 that pushes the first n elements of a sequence on the stack.

Examples
Some core words expressed in terms of firstn:

first	1 firstn
first2	2 firstn
first3	3 firstn
first4	4 firstn

Definition

USING: kernel math sequences ;

IN: sequences.generalizations

MACRO: firstn ( n -- quot )
    [ [ drop ] ] [
        [ 1 - swap bounds-check 2drop ] [ firstn-unsafe ]
        bi-curry [ bi ] 2curry
    ] if-zero ;