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

wutsig, ?~, %wtsg

If ~

?~ is a synthetic rune that produces q if p is ~, r otherwise.

Produces

Twig: [%wtsg p=wing q=twig r=twig]

Sample

p is a ++wing. q and r are twigs.

Tall form

?~  p
  q
r

Wide form

?~(p q r)

Irregular form

None

Examples

~zod/try=> ?~('a' 1 2)
2
~zod/try=> ?~('' 1 2)
1
~zod/try=> ?~(~zod 1 2)
1
~zod/try=> ?~((sub 20 20) 1 2)
1

Equivalent to

?:(?=(~ p) q r)