urbit/pub/docs/dev/hoon/runes/wt/wtcl.md

wutcol, ?:, %wtcl

If, then

?:, wutcol, is a natural rune that produces q if p is yes (&, 0), or r if p is no (|, 1). ?: is most similar to the traditional "if" statement, producing the first expression if the loobean is true. ?: is the inverse of ?..

See also

wutdot, ?., %wtdt

Produces

Twig: [%wtcl p=twig q=twig r=twig]

Sample

p, q, and r are twigs.

Tall form

?:  p
  q
r

Wide form

?:(p q r)

Irregular form

None

Examples

~zod/try=> ?:((gth 1 2) 1 2)
2
~zod/try=> ?:(?=(%a 'a') %yup %not-a)
%yup

Here we see two common cases of ?: in the wide form, one uses an expression gte that produces a loobean and the other ?= to produce one of its cases.