urbit/base/pub/doc/hoon/runes/wt/wtpt.md
2015-04-29 18:48:45 -04:00

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[wutpat, `?@`, %wtpt](#wtpt)
============================
If atom
`?@` is a synthetic rune that produces `q` if `p` is an atom, `r`
otherwise.
Produces
--------
Twig: `[%wtpt p=wing q=twig r=twig]`
Sample
------
`p` is a [`++wing`](). `q` and `r` are [twig]()s.
Tall form
---------
Kingside:
?@ p
q
r
Wide form
---------
?@(p q r)
Irregular form
--------------
None
Examples
--------
~zod/try=> ?@(~ 1 2)
! mint-vain
! exit
~zod/try=> ?@(%ha 1 2)
1
~zod/try=> ?@("" 1 2)
1
~zod/try=> ?@("a" 1 2)
2
~zod/try=> ?@([1 1] 1 2)
! mint-vain
! exit
~zod/try=> ?@(`*`[1 1] 1 2)
2