?firstn ( n -- quot )

Vocabulary

sequences.generalizations

Inputs

n	an integer

Outputs

None

Word description

A generalization of ?first that pushes the first n elements of a sequence on the stack, or f if the sequence is shorter than the requested number of elements.

Examples

Some core words expressed in terms of ?firstn:

?first

1 ?firstn

Definition

USING: kernel sequences.padded ;

IN: sequences.generalizations

MACRO: ?firstn ( n -- quot )
    dup [ [ f <padded-tail> ] curry ] dip
    [ firstn-unsafe ] curry compose ;