Runes

Question 1

.+

Answer 1

Increment an atom.

e.g. .+(1) produces 2

Question 2

.=

Answer 2

Test for equality. If equal, produces %.y; otherwise %.n.

e.g. .=(1 1) produces %.y

Question 3

.?

Answer 3

Test for cell or atom. Produces %.y if p is a cell; otherwise %.n.

Question 4

?>

Answer 4

Positive assertion. If p = q then return %.y; otherwise force crash.

Question 5

?:

Answer 5

Branch on a boolean test. If p produces yes, %.y, then q. If p produces no, %.n, then r.

Question 6

?.

Answer 6

Branch on a boolean test, inverted. For when yes-case is much taller / wider than the no-case; aesthetic.

Question 7

?[gal]

Answer 7

Negative assertion. If %.y, force crash.

Question 8

?&

Answer 8

Boolean AND.

Question 9

?=

Answer 9

Test type. Returns %.y or %.n.

Question 10

?!

Answer 10

Boolean NOT

Question 11

|=

Answer 11

Create a gate (aka a function)

e.g. |= end=@

Creates function, specifying it takes one argument, which we named “end”, and “@” specifies the input is an atom.

Question 12

=/

Answer 12

Store a value with a name and a specified type

e.g. =/ count=@ 1

count=@ (the first child) stores 1 (the second child) as count and specifies that it has the @ type

This is as close as you’ll get to a variable

Question 13

|-

Answer 13

Produce a trap (a core with one arm $) and evaluate it. Can be thought of as a ‘recursion point’ or a ‘loop starting point’.

Question 14

^-

Answer 14

Use in a gate to constrain output to a certain type

e.g. ^- (list @)

Specifies that our gate’s output must be (list @) — that is, a list of atoms

Question 15

:-

Answer 15

Create a cell.

Question 16

+|

Answer 16

Provides a label for the arms that follow.

The arms of a core can be divided into chapters for ‘organization’. Chapter labels aren’t part of the underlying noun of the core; they’re stored as type system metadata only.

e.g. +| %math

Question 17

++

Answer 17

Produce a normal arm.

e.g.
\++  add
  ~/  %add
  ::  unsigned addition
  ::
  ::  a: augend
  ::  b: addend
  |=  [a=@ b=@]
  ::  sum
  ^-  @
  ?:  =(0 a)  b
  $(a (dec a), b +(b))

Question 18

|%

Answer 18

Produces a core.

Question 19

–

Answer 19

Indicate there are no more arms to be defined.

Question 20

=.

Answer 20

Changes the leg of the subject to something else.

Question 21

=

Answer 21

Compose two expressions, inverted for aesthetic reasons.

Question 22

=>

Answer 22

Compose two expressions.

Question 23

=~

Answer 23

Compose multiple expressions.

Question 24

/-

Answer 24

Import library from sur

Question 25

/+

Answer 25

Import library from lib

Question 26

=,

Answer 26

Expose a namespace.