??nth ( n seq -- elt/f ? )

Vocabulary

sequences.extras

Inputs

n	an integer
seq	a sequence

Outputs

elt/f	an object or f
?	a boolean

Word description

A forgiving version of nth. If the index is out of bounds, or if the sequence is f, simply outputs f. Also outputs a boolean to distinguish between the sequence containing an f or an out of bounds index.

Definition

USING: kernel sequences sequences.private ;

IN: sequences.extras

: ??nth ( n seq -- elt/f ? )
    2dup bounds-check? [ nth-unsafe t ] [ 2drop f f ] if ;
    inline