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      • 1a: Basic Arithmetic
      • 1b: Tree Addressing
      • 1c: Molds and Mold-Builders
      • 2a: Unit Logic
      • 2b: List Logic
      • 2c: Bit Arithmetic
      • 2d: Bit Logic
      • 2e: Insecure Hashing
      • 2f: Noun Ordering
      • 2g: Unsigned Powers
      • 2h: Set Logic
      • 2i: Map Logic
      • 2j: Jar and Jug Logic
      • 2k: Queue Logic
      • 2l: Container from Container
      • 2m: Container from Noun
      • 2n: Functional Hacks
      • 2o: Normalizing Containers
      • 2p: Serialization
      • 2q: Molds and Mold-Builders
      • 3a: Modular and Signed Ints
      • 3b: Floating Point
      • 3c: Urbit Time
      • 3d: SHA Hash Family
      • 3e: AES encryption (Removed)
      • 3f: Scrambling
      • 3g: Molds and Mold-Builders
      • 4a: Exotic Bases
      • 4b: Text Processing
      • 4c: Tank Printer
      • 4d: Parsing (Tracing)
      • 4e: Parsing (Combinators)
      • 4f: Parsing (Rule-Builders)
      • 4g: Parsing (Outside Caller)
      • 4h: Parsing (ASCII Glyphs)
      • 4i: Parsing (Useful Idioms)
      • 4j: Parsing (Bases and Base Digits)
      • 4k: Atom Printing
      • 4l: Atom Parsing
      • 4m: Formatting Functions
      • 4n: Virtualization
      • 4o: Molds
      • 5a: Compiler Utilities
      • 5b: Macro Expansion
      • 5c: Compiler Backend & Prettyprinter
      • 5d: Parser
      • 5e: Molds and mold builders
      • 5f: Profiling support
      • Runes

        • Constants (Atoms and Strings)
        • + lus · Arms
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        • . dot · Nock
        • / fas · Imports
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        • ; mic · Make
        • ~ sig · Hints
        • = tis · Subject
        • ? wut · Conditionals
        • ! zap · Wild
        • --, == Terminators
        • Limbs and wings

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            • 2d(1-5): To JSON, Wains
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                                                    Urbit Developers
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                                                      • Standard Library

                                                        • 1a: Basic Arithmetic
                                                        • 1b: Tree Addressing
                                                        • 1c: Molds and Mold-Builders
                                                        • 2a: Unit Logic
                                                        • 2b: List Logic
                                                        • 2c: Bit Arithmetic
                                                        • 2d: Bit Logic
                                                        • 2e: Insecure Hashing
                                                        • 2f: Noun Ordering
                                                        • 2g: Unsigned Powers
                                                        • 2h: Set Logic
                                                        • 2i: Map Logic
                                                        • 2j: Jar and Jug Logic
                                                        • 2k: Queue Logic
                                                        • 2l: Container from Container
                                                        • 2m: Container from Noun
                                                        • 2n: Functional Hacks
                                                        • 2o: Normalizing Containers
                                                        • 2p: Serialization
                                                        • 2q: Molds and Mold-Builders
                                                        • 3a: Modular and Signed Ints
                                                        • 3b: Floating Point
                                                        • 3c: Urbit Time
                                                        • 3d: SHA Hash Family
                                                        • 3e: AES encryption (Removed)
                                                        • 3f: Scrambling
                                                        • 3g: Molds and Mold-Builders
                                                        • 4a: Exotic Bases
                                                        • 4b: Text Processing
                                                        • 4c: Tank Printer
                                                        • 4d: Parsing (Tracing)
                                                        • 4e: Parsing (Combinators)
                                                        • 4f: Parsing (Rule-Builders)
                                                        • 4g: Parsing (Outside Caller)
                                                        • 4h: Parsing (ASCII Glyphs)
                                                        • 4i: Parsing (Useful Idioms)
                                                        • 4j: Parsing (Bases and Base Digits)
                                                        • 4k: Atom Printing
                                                        • 4l: Atom Parsing
                                                        • 4m: Formatting Functions
                                                        • 4n: Virtualization
                                                        • 4o: Molds
                                                        • 5a: Compiler Utilities
                                                        • 5b: Macro Expansion
                                                        • 5c: Compiler Backend & Prettyprinter
                                                        • 5d: Parser
                                                        • 5e: Molds and mold builders
                                                        • 5f: Profiling support
                                                        • Runes

                                                          • Constants (Atoms and Strings)
                                                          • + lus · Arms
                                                          • | bar · Cores
                                                          • $ buc · Structures
                                                          • % cen · Calls
                                                          • : col · Cells
                                                          • . dot · Nock
                                                          • / fas · Imports
                                                          • ^ ket · Casts
                                                          • ; mic · Make
                                                          • ~ sig · Hints
                                                          • = tis · Subject
                                                          • ? wut · Conditionals
                                                          • ! zap · Wild
                                                          • --, == Terminators
                                                          • Limbs and wings

                                                            • Limbs
                                                            • Wings
                                                            • Zuse

                                                              • 2d(1-5): To JSON, Wains
                                                              • 2d(6): From JSON
                                                              • 2d(7): From JSON (unit)
                                                              • 2e(2-3): Print & Parse JSON
                                                              • 2m: Ordered Maps
                                                            • Arvo

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                                                                • API Reference
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                                                                                                      Reference/Hoon/Standard Library

                                                                                                      1c: Molds and Mold-Builders

                                                                                                      +$bite

                                                                                                      Atom slice specifier.

                                                                                                      Either a single atom representing block size, or a cell containing a block size and an atom representing the number of blocks, called step. If step is not supplied, it defaults to a value of 1.

                                                                                                      Source

                                                                                                      +$ bite $@(bloq [=bloq =step])

                                                                                                      Examples

                                                                                                      :: ++end gets the least significant bits of an atom.
                                                                                                      > (end [1 1] 255)
                                                                                                      3
                                                                                                      > (end 1 255)
                                                                                                      3
                                                                                                      > (end 3 255)
                                                                                                      255
                                                                                                      > (end 3 65.535)
                                                                                                      255
                                                                                                      > (end [3 2] 65.535)
                                                                                                      65.535
                                                                                                      > (end [3 0] 65.535)
                                                                                                      0

                                                                                                      +$bloq

                                                                                                      Blocksize

                                                                                                      Atom representing block size. A block of size a has a bitwidth of 2^a.

                                                                                                      Source

                                                                                                      ++ bloq @

                                                                                                      Examples

                                                                                                      :: ++met measures how many a-bloqs long an atom is.
                                                                                                      > (met 3 256)
                                                                                                      2
                                                                                                      > (met 3 255)
                                                                                                      1
                                                                                                      > (met 3 65.535)
                                                                                                      2
                                                                                                      > (met 2 65.536)
                                                                                                      > 3
                                                                                                      > (met 0 4)
                                                                                                      3
                                                                                                      > (met 1 4)
                                                                                                      2
                                                                                                      > (met 5 9.999.999.999)
                                                                                                      2
                                                                                                      > (met 2 0xb5)
                                                                                                      2

                                                                                                      Discussion

                                                                                                      You can think of bloq as a numeral system that can represent values of a^2^2, where a is the block size. That's because a block of size a contains a^2 bits, and a binary number that is b bits wide can represent b^2 values.

                                                                                                      A bloq of 0 has a bitwidth of 1. (2^0 bits; can represent 2 values.)

                                                                                                      A bloq of 1 has a bitwidth of 2. (2^1 bits; can represent 4 values.)

                                                                                                      A bloq of 2 has a bitwidth of 4. (2^2 bits; can represent 16 values.)

                                                                                                      A bloq of 3 has a bitwidth of 8. (2^3 bits; can represent 256 values.)

                                                                                                      And so on.

                                                                                                      See the bit arithmetic section for operations that use bloqs.


                                                                                                      ++each

                                                                                                      Mold of fork between two types

                                                                                                      A mold generator. Produces a discriminated fork between two types, defaulting to this.

                                                                                                      Source

                                                                                                      ++ each
                                                                                                      |$ [this that]
                                                                                                      $% [%| p=that]
                                                                                                      [%& p=this]
                                                                                                      ==

                                                                                                      Examples

                                                                                                      > ? *(each cord time)
                                                                                                      ?([%.y p=@t] [%.n p=@da])
                                                                                                      [%.y p='']
                                                                                                      > ? *(each * tape)
                                                                                                      ?([%.y p=*] [%.n p=""])
                                                                                                      [%.y p=0]

                                                                                                      ++gate

                                                                                                      Function

                                                                                                      A core with one arm, $--the empty name--which transforms a sample noun into a product noun. If used dryly as a type, the subject must have a sample type of *.

                                                                                                      Source

                                                                                                      ++ gate
                                                                                                      $-(* *)

                                                                                                      Examples

                                                                                                      > ? gate
                                                                                                      <1.ddq [* <46.hgz 1.pnw %140>]>
                                                                                                      <1.ddq [* <46.hgz 1.pnw %140>]>
                                                                                                      > (`gate`|=(a=* [a 'b']) 1)
                                                                                                      [1 98]
                                                                                                      > (`gate`|=(a=@ [a 'b']) 1)
                                                                                                      mint-nice
                                                                                                      -need.@
                                                                                                      -have.*
                                                                                                      nest-fail
                                                                                                      dojo: hoon expression failed

                                                                                                      Discussion

                                                                                                      A gate is analogous to a function in other programming languages. We created this new jargon because other constructs in Urbit are "functions" in the mathematical sense. Any gate normalizes to an iron gate.

                                                                                                      See also: ++lift, ++cork


                                                                                                      ++list

                                                                                                      List

                                                                                                      A mold generator. Generates a mold of a null-terminated list of a homogenous type.

                                                                                                      Source

                                                                                                      ++ list
                                                                                                      |$ [item]
                                                                                                      $@(~ [i=item t=(list item)])

                                                                                                      Examples

                                                                                                      > *(list)
                                                                                                      ~
                                                                                                      > `(list @)`"abc"
                                                                                                      ~[97 98 99]
                                                                                                      > (snag 0 "abc")
                                                                                                      'a'
                                                                                                      > `(list @)`[1 2 'j' ~]
                                                                                                      ~[1 2 106]

                                                                                                      Discussion

                                                                                                      See also: ++turn, ++snag


                                                                                                      ++lone

                                                                                                      Face on mold

                                                                                                      A mold generator. Puts face of p on the passed-in mold.

                                                                                                      Source

                                                                                                      ++ lone
                                                                                                      |$ [item]
                                                                                                      p=item

                                                                                                      Examples

                                                                                                      > ? *cord
                                                                                                      @t
                                                                                                      ''
                                                                                                      > ? *(lone cord)
                                                                                                      p=@t
                                                                                                      p=''
                                                                                                      > ? *(lone @)
                                                                                                      p=@
                                                                                                      p=0
                                                                                                      > ? *@
                                                                                                      @
                                                                                                      0

                                                                                                      ++pair

                                                                                                      Mold of pair of types

                                                                                                      A mold generator. Produces a tuple of two of the types passed in.

                                                                                                      Source

                                                                                                      ++ pair
                                                                                                      |$ [head tail]
                                                                                                      [p=head q=tail]

                                                                                                      Examples

                                                                                                      > *(pair ? cord)
                                                                                                      [p=%.y q='']
                                                                                                      > *(pair tape @)
                                                                                                      [p="" q=0]

                                                                                                      ++pole

                                                                                                      Faceless list

                                                                                                      A mold generator. A list without the faces i and t.

                                                                                                      Source

                                                                                                      ++ pole
                                                                                                      |$ [item]
                                                                                                      $@(~ [item (pole item)])

                                                                                                      Examples

                                                                                                      > =/(a "asdf" ?>(?=(^ a) `(lest @tD)`a))
                                                                                                      [i='a' t=[i='s' t=[i='d' t=[i='f' t=~]]]]
                                                                                                      > `(pole char)`"asdf"
                                                                                                      ['a' ['s' ['d' ['f' ~]]]]

                                                                                                      ++qual

                                                                                                      Mold of 4-type tuple

                                                                                                      A mold generator. Produces a tuple of four of the types passed in.

                                                                                                      Source

                                                                                                      ++ qual
                                                                                                      |$ [first second third fourth]
                                                                                                      [p=first q=second r=third s=fourth]

                                                                                                      Examples

                                                                                                      > *(qual date time tape cord)
                                                                                                      [p=[[a=%.y y=0] m=0 t=[d=0 h=0 m=0 s=0 f=~]] q=~2000.1.1 r="" s='']
                                                                                                      > *(qual (list @) @u @ud @ux)
                                                                                                      [p=~ q=0 r=0 s=0x0]

                                                                                                      ++quip

                                                                                                      Mold of pair of list and type

                                                                                                      A mold generator. Produces a tuple of a list of item and the mold of state.

                                                                                                      Source

                                                                                                      ++ quip
                                                                                                      |$ [item state]
                                                                                                      [(list item) state]

                                                                                                      Examples

                                                                                                      > *(quip @ _'hi')
                                                                                                      [~ 'hi']
                                                                                                      > `(quip @ @ux)`[[1 2 3 4 ~] 0x10]
                                                                                                      [~[1 2 3 4] 0x10]

                                                                                                      Discussion

                                                                                                      A common pattern in Hoon code is to return a list of changes, along with a new state. You'll often see quip used in Gall apps.


                                                                                                      ++step

                                                                                                      Atom size or offset, in bloqs.

                                                                                                      Source

                                                                                                      ++ step
                                                                                                      _`@u`1

                                                                                                      Examples

                                                                                                      > `step`0
                                                                                                      0
                                                                                                      > `step`2
                                                                                                      2

                                                                                                      ++trap

                                                                                                      Core with one arm $

                                                                                                      A trap is a core with one arm $.

                                                                                                      Source

                                                                                                      ++ trap
                                                                                                      |$ [product]
                                                                                                      _|?($:product)

                                                                                                      Examples

                                                                                                      > (*trap)
                                                                                                      <1?ruo 1.mhl [product=<1|xpg [* * *]> <46.hgz 1.pnw %140>]>
                                                                                                      > *(*trap)
                                                                                                      0
                                                                                                      > (|.(42))
                                                                                                      42

                                                                                                      ++tree

                                                                                                      Tree mold generator

                                                                                                      A mold generator. A tree can be empty, or contain a node of a type and left/right sub tree of the same type. Pretty-printed with {}.

                                                                                                      Source

                                                                                                      ++ tree
                                                                                                      |$ [node]
                                                                                                      $@(~ [n=node l=(tree node) r=(tree node)])

                                                                                                      Examples

                                                                                                      > `(tree [@ tape])`[[1 "hi"] [[2 "bye"] ~ ~] ~]
                                                                                                      {[2 "bye"] [1 "hi"]}

                                                                                                      ++trel

                                                                                                      Mold of three types

                                                                                                      A mold generator. A mold of the tuple of the three types passed in.

                                                                                                      Source

                                                                                                      ++ trel
                                                                                                      |$ [first second third]
                                                                                                      [p=first q=second r=third]

                                                                                                      Examples

                                                                                                      > *(trel @ud @t @s)
                                                                                                      [p=0 q='' r=--0]
                                                                                                      > *(trel cord bloq tape)
                                                                                                      [p='' q=0 r=""]

                                                                                                      ++unit

                                                                                                      Maybe

                                                                                                      A mold generator. A unit is either ~ or [~ u=item], where item is the type that was passed in.

                                                                                                      Source

                                                                                                      ++ unit
                                                                                                      |$ [item]
                                                                                                      $@(~ [~ u=item])

                                                                                                      Examples

                                                                                                      > ? *(unit time)
                                                                                                      u(@da)
                                                                                                      ~
                                                                                                      > =a |= a=@
                                                                                                      ^- (unit @)
                                                                                                      ?~ a ~
                                                                                                      [~ a]
                                                                                                      > (a 2)
                                                                                                      [~ 2]

                                                                                                      Discussion

                                                                                                      Using a unit allows you to specify something that may not be there.

                                                                                                      See also: ++bind


                                                                                                      <-

                                                                                                      1b: Tree Addressing

                                                                                                      2a: Unit Logic

                                                                                                      ->

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                                                                                                      Last modified September 22, 2023