when-empty ( seq quot -- )
Factor handbook > The language > Collections > Sequence operations > Control flow with sequences

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Vocabulary
sequences

Inputs and outputs
seqa sequence
quotthe first quotation of an if-empty


Word description
Makes an implicit check if the sequence is empty. An empty sequence is dropped and the quot is called.

Examples
This word is equivalent to if-empty with an empty second quotation:
USING: sequences prettyprint ; { } [ { 4 5 6 } ] [ ] if-empty .
{ 4 5 6 }

USING: sequences prettyprint ; { } [ { 4 5 6 } ] when-empty .
{ 4 5 6 }


Definition