Urbit / Docs

Irregular forms, a compilation

~palfun-foslup
Reading guide

Headings contain runes, phonetics and tokens. Description contains a link to the docs and a short description of the rune. Both regular (R) and irregular (I) forms are given.

Want to Ctrl-f to find out the meaning of something weird you saw? Search for \symbol. ie \? or \=. It'll show you to the irregular forms that uses that symbol.

. dot (nock)

Anything Nock can do, Hoon can do also.

.+ dotlus

docs \+ [%dtls p=atom]: increment an atom with Nock 4.

R: .+(p) I: +(p)

.= dottis

docs \= [%dtls p=hoon q=hoon]: test for equality with Nock 5.

R: .=(p q) I: =(p q)

; mic (make)

Miscellaneous useful macros.

;: miccol

docs \: [%smcl p=hoon q=(list hoon)]: call a binary function as an n-ary function.

R: ;:(p q) I: :(p q)

: col (cells)

The cell runes.

:- colhep

docs \[\]\^\+\`\~ [%clhp p=hoon q=hoon]: construct a cell (2-tuple).

R: :-(p q) I:

  [a b]   ==>   :-(a b)
[a b c]   ==>   [a [b c]]
  a^b^c   ==>   [a b c]
    a/b   ==>   [%a b]
     `a   ==>   [~ a]
 ~[a b]   ==>   [a b ~]
  [a b]~  ==>   [[a b] ~]

= tis (flow)

Flow hoons change the subject. All non-flow hoons (except cores) pass the subject down unchanged.

=< tisgar

docs \: [%tsgl p=hoon q=hoon]: compose two hoons, inverted.

R: =<(p q) I: p:q

| bar (core)

docs \$ Core hoons are flow hoon.

Technically not irregular syntax, but worth mentioning.

  • |= bartis

  • |. bardot

  • |- barhep

  • |* bartar

The above runes produce a core with a single arm, named $ (“buc”). We can recompute this arm with changes, useful for recursion among other things. Commonly used with the irregular syntax for %=, :make, like so: $().

% cen (call)

The invocation family of runes.

%= centis

docs \(\) [%cnts p=wing q=(list (pair wing hoon))]: take a wing with changes.

R: %=(p a 1) I: p(a 1)

%~ censig

docs \~ [%cnsg p=wing q=hoon r=hoon]: call with multi-armed door.

R: %~(p q r) I: ~(p q r)

%- cenhep

docs \(\) [%cnhp p=hoon q=hoon]: call a gate (function).

R: %-(p q) I: (p q)

Note: (p) becomes $:p (=<($ p)), which behaves as you would expect (func call w/o args).

$ buc (mold)

A mold is a gate (function) that helps us build simple and rigorous data structures.

$? bucwut

docs \? [%bcwt p=(list model)]: mold which normalizes a general union.

R: $?(p) I: ?(p)

$_ buccab

docs \_ [%bccb p=value]: mold which normalizes to an example.

R: $_(p) I: _p

? wut (test)

Hoon has the usual branches and logical tests.

?! wutzap

docs \! [%wtzp p=hoon]: logical not.

R: ?!(p) I: !(p)

?& wutpam

docs \& [%wtpm p=(list hoon)]: logical and.

R: ?&(p) I: &(p)

?| wutbar

docs \| [%wtbr p=(list hoon)]: logical or.

R: ?|(p) I: |(p)

^ ket (cast)

Lets us adjust types without violating type constraints.

^- kethep

docs \` [%kthp p=model q=value]: typecast by mold.

R: ^-(p q) I: pq

^= kettis

docs \= [%ktts p=toga q=value]: name a value.

R: ^=(p q) I: p=q

Miscellaneous

Trivial molds

\*\^\?

  • * noun.

  • @ atom.

  • ^ cell.

  • ? loobean.

  • ~ null.

Values

\~\-\.\&\|

  • ~ null.

  • & loobean true.

  • | loobean false.

  • %a constant a, where a can be an ((ir)regularly defined) atom or a symbol.

See %sand for other irregular definitions of atoms.

List addressing

  • &n nth element of a list.

  • |n tail of list after nth element (i.e. n is the head).

Limbs

docs \+\.\^ [%limb p=(each @ud [[email protected] [email protected]])]: attribute of subject.

  • +15 is slot 15

  • . is the whole subject (slot 1)

  • ^a is the a “of a higher scope”, i.e. “resolve variable a, ignoring the first one found”.

  • ^^p even higher, etc.

  • 'Lark' syntax for slots / tree addressing:

+1
+2 -
+3 +
+4 -<
+5 ->
+6 +<
+7 +>
+8 -<-
...

Wings

docs [%wing p=(list limb)]; a limb search path. a.b finds limb a within limb b (“var” a within “var” b).

Printing stuff

  • <a b c> prints a tape.

  • >a b c< prints a tank.

Commentary

In our in-house examples throughout our documentation, we use irregular forms instead of regular for the sake of verbosity. But remember with irregular forms: everything is just runes! Like magic. In general, irregular forms (usually) read better, but of course regular forms provide more information about what you're doing by showing you the full rune. Of course, it's up to you, the Hoon programmer, as to whether or not you want to use these.

If we missed any, or if you saw something weird that's not in here, feel free to comment below!