Glossary Flashcards
Atom
A natural number >= 0.
These numbers often referred to as “unsigned integers”.
Arm
Subject limb used for carrying out computations.
Aura
A soft type that declares if an atom is a date, a ship name, a number, etc.
“Soft” means: you can cast an atom of any aura as any other aura.
Battery
A collection of one or more arms.
Behn
Urbit OS’s timer vane
Binary tree
A tree of nested pairs; the structure of all data in Nock and Hoon.
Bind
To assign a value to a face.
Bunt value
The default value for any given type.
e.g. the bunt of an atom is 0.
Cast
To represent an atom as a specific datatype.
Cask
A pair consisting of a mark and some data.
e.g. [mark data]
Cell
An ordered pair of nouns.
All data in Hoon that is not an atom is stored as a cell.
Clay
Urbit OS’s filesystem and revision-control vane.
Context
Data available to your program that hasn’t been explicitly provided.
Core
A cell consisting of [battery payload].
The battery is code and the payload is data for that code.
Dill
Urbit OS’ terminal-driver vane.
Door
A core with a sample, whose payload is a cell of sample and context: [sample context].
e.g. [battery [sample context]].
Dry gate
A gate with a specified type.
Expression
Any combination of characters Hoon interprets to produce a value.
Eyre
Urbit OS’s HTTP vane.
Face
The closest thing Hoon has to a variable. Can store code or data.
Ford
Urbit OS’s build-system vane.
Gate
A Hoon “function”. A gate has two elements: [battery payload].
Generator
A Hoon program.
Head
The left-most part of a cell.
Iris
Urbit OS’s server HTTP vane.
Jael
Urbit OS’s security vane.
Leg
Subject limb which stores data. Any limb which isn’t an arm is a leg.
Leaf
Generally refers to a data-only branch of a binary tree.
Limb
A subtree of the subject, when represented as a binary tree.
List
A cell with an ordered list of items, terminated by a sig.
e.g ~[foo bar baz]
Map
A dictionary of key-value pairs.
Mold
A function that “coerces” a noun into a type or crashes.
Naked generator
A generator that takes one argument and produces some output.
This single argument can have arbitrarily many parts.
Noun
An atom or a cell.
Null list
A list containing nothing, represented by sig.
e.g. [~]
p
Head.
Payload
The data needed by the arms to evaluate correctly.
Pier
The file folder where an urbit ship’s files are stored.
q
Tail.
Sample
The part of the payload that stores the input value / argument.
Subject
Noun which defines the environment in which its contained expression is evaluated.
Trap
A recursion loop.
Type
A set of nouns.
Vane
An Urbit OS module that performs essential system operations.
The modules are ames, behn, clay, dill, eyre, ford, gall, iris, jael.
Vere
The urbit virtual machine.
Pronounced “vair”.
Wet core
A core without specified types.
Wing
An arm or a leg, or a path of arms and legs.
