Glossary

Question 1

Atom

Answer 1

A natural number >= 0.

These numbers often referred to as “unsigned integers”.

Question 2

Arm

Answer 2

Subject limb used for carrying out computations.

Question 3

Aura

Answer 3

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.

Question 4

Battery

Answer 4

A collection of one or more arms.

Question 5

Behn

Answer 5

Urbit OS’s timer vane

Question 6

Binary tree

Answer 6

A tree of nested pairs; the structure of all data in Nock and Hoon.

Question 7

Bind

Answer 7

To assign a value to a face.

Question 8

Bunt value

Answer 8

The default value for any given type.

e.g. the bunt of an atom is 0.

Question 9

Cast

Answer 9

To represent an atom as a specific datatype.

Question 10

Cask

Answer 10

A pair consisting of a mark and some data.

e.g. [mark data]

Question 11

Cell

Answer 11

An ordered pair of nouns.

All data in Hoon that is not an atom is stored as a cell.

Question 12

Clay

Answer 12

Urbit OS’s filesystem and revision-control vane.

Question 13

Context

Answer 13

Data available to your program that hasn’t been explicitly provided.

Question 14

Core

Answer 14

A cell consisting of [battery payload].

The battery is code and the payload is data for that code.

Question 15

Dill

Answer 15

Urbit OS’ terminal-driver vane.

Question 16

Door

Answer 16

A core with a sample, whose payload is a cell of sample and context: [sample context].

e.g. [battery [sample context]].

Question 17

Dry gate

Answer 17

A gate with a specified type.

Question 18

Expression

Answer 18

Any combination of characters Hoon interprets to produce a value.

Question 19

Eyre

Answer 19

Urbit OS’s HTTP vane.

Question 20

Face

Answer 20

The closest thing Hoon has to a variable. Can store code or data.

Question 21

Ford

Answer 21

Urbit OS’s build-system vane.

Question 22

Gate

Answer 22

A Hoon “function”. A gate has two elements: [battery payload].

Question 23

Generator

Answer 23

A Hoon program.

Question 24

Head

Answer 24

The left-most part of a cell.

Question 25

Iris

Answer 25

Urbit OS’s server HTTP vane.

Question 26

Jael

Answer 26

Urbit OS’s security vane.

Question 27

Leg

Answer 27

Subject limb which stores data. Any limb which isn’t an arm is a leg.

Question 28

Leaf

Answer 28

Generally refers to a data-only branch of a binary tree.

Question 29

Limb

Answer 29

A subtree of the subject, when represented as a binary tree.

Question 30

List

Answer 30

A cell with an ordered list of items, terminated by a sig.

e.g ~[foo bar baz]

Question 31

Map

Answer 31

A dictionary of key-value pairs.

Question 32

Mold

Answer 32

A function that “coerces” a noun into a type or crashes.

Question 33

Naked generator

Answer 33

A generator that takes one argument and produces some output.

This single argument can have arbitrarily many parts.

Question 34

Noun

Answer 34

An atom or a cell.

Question 35

Null list

Answer 35

A list containing nothing, represented by sig.

e.g. [~]

Question 36

p

Answer 36

Head.

Question 37

Payload

Answer 37

The data needed by the arms to evaluate correctly.

Question 38

Pier

Answer 38

The file folder where an urbit ship’s files are stored.

Question 39

q

Answer 39

Tail.

Question 40

Sample

Answer 40

The part of the payload that stores the input value / argument.

Question 41

Subject

Answer 41

Noun which defines the environment in which its contained expression is evaluated.

Question 42

Trap

Answer 42

A recursion loop.

Question 43

Type

Answer 43

A set of nouns.

Question 44

Vane

Answer 44

An Urbit OS module that performs essential system operations.

The modules are ames, behn, clay, dill, eyre, ford, gall, iris, jael.

Question 45

Vere

Answer 45

The urbit virtual machine.

Pronounced “vair”.

Question 46

Wet core

Answer 46

A core without specified types.

Question 47

Wing

Answer 47

An arm or a leg, or a path of arms and legs.