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urbit.org/docs/programming/reference/library/src/4e/gate/fail.md
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1### `++fail`
3Never parse
5Produces an `++edge` at the same text position (`++hair`) with a failing
6result (`q=~`).
8Accepts
9-------
11`tub` is a `++nail`.
13Produces
14--------
16An `++edge`.
18Source
19------
21 ++ fail |=(tub/nail [p=p.tub q=~]) :: never parse
23Examples
24--------
26 ~zod/try=> (fail [[1 1] "abc"])
27 [p=[p=1 q=1] q=~]
28 ~zod/try=> (fail [[p=1.337 q=70] "Parse me, please?"])
29 [p=[p=1.337 q=70] q=~]
33***