1guard ( ..a x quot: ( ..a x -- ..b ? ) -- ..b x/f )
Factor handbook » The language » Combinators » Conditional combinators

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Vocabulary
kernel

Inputs

x	an object
quot	a quotation

Outputs

x/f

an object

Word description
Calls quot on x and either keeps x or replaces it with f.

Examples
True case:

USING: kernel math prettyprint ; 6 [ even? ] 1guard .
6

False case:

USING: kernel math prettyprint ; 5 [ even? ] 1guard .
f

See also
1check, 2check, 2guard, 3check, 3guard

Definition

IN: kernel

: 1guard ( ..a x quot: ( ..a x -- ..b ? ) -- ..b x/f )
    1check [ drop f ] unless ; inline