?first ( seq -- elt/f )
Factor handbook > The language > Collections > Sequence operations > Accessing sequence elements

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Vocabulary
sequences

Inputs and outputs
seqa sequence
elt/fan object or f


Word description
A forgiving version of first. If the sequence is empty, or if the sequence is f, simply outputs f.

Examples
On an empty sequence:
USING: sequences prettyprint ; { } ?first .
f

Works like first on sequences with elements:
USING: sequences prettyprint ; { 1 2 3 } ?first .
1


Definition