?first4 ( seq -- first/f second/f third/f fourth/f )

Vocabulary

sequences.extras

Inputs

seq	a sequence

Outputs

first/f	an object
second/f	an object
third/f	an object
fourth/f	an object

Word description

Pushes the first four elements of seq. Pushes f for missing elements.

Definition

USING: combinators kernel sequences sequences.private ;

IN: sequences.extras

: ?first4 ( seq -- first/f second/f third/f fourth/f )
    dup length {
        { 0 [ drop f f f f ] }
        { 1 [ first-unsafe f f f ] }
        { 2 [ first2-unsafe f f ] }
        { 3 [ first3-unsafe f ] }
        [ drop first4-unsafe ]
    } case ;