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

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[sigwut, `~?`, %sgwt](#sgwt)
============================
Conditional printf
`~?` is a synthetic rune with the same hint effect as `~&`, printing `r`
if and only if `q` produces `&`, loobean yes.
Produces
--------
Twig: `[%sgwt p=@ud q=twig r=twig s=twig]`
Sample
------
`p` is a [`@ud`](). `q` is a [twig](). `r` is a [twig](). `s` is a
[twig]().
Tall form
---------
Priority 0 (debug):
~& q
r
Priority 1 (notice):
~& > q
r
Priority 2 (warning):
~& >> q
r
Priority 3 (alarm):
~& >>> q
r
Wide form
---------
~&(>> q r)
Irregular form
--------------
None
Examples
--------
~zod/try=> ~?((gth 1 2) 'oops' ~)
~
~zod/try=> ~?((gth 1 0) 'oops' ~)
'oops'
~
A simple case of the conditional printf. When our condition evaluates to
`&` we print our `r`. Most useful in computation dealing with dynamic
data.