urbit/pub/doc/hoon/runes/sg/sgpm.md

sigpam, ~&, %sgpm

printf

~&, sigpam, is a synthetic rune that prints q on the console before computing r. p is the log priority, 0-3 defaulting to 0. ~& is similar to printf or log in other languages, and is very commonly used for debugging.

Produces

Twig: [%sgpm p=@ud q=twig r=twig]

Sample

p is a @ud q is a twig r 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

undefined

Examples

~zod/try=> ~
~
~zod/try=> ~&('oops' ~)
'oops'
~

The most common use of ~&: print something to the console before proceeding.