# 2q: Molds and Mold-Builders ## `$axis` Tree address. A Nock axis inside a `$noun`. After the leading 1, in binary, a `1` signfies right and `0` left. #### Source ```hoon +$ axis @ ``` #### Examples ``` > =axis `axis`7 > axis 7 > `@ub`axis 0b111 > =noun [[4 5] [6 14 15]] > .*(noun [0 axis]) [14 15] ``` *** ## `$bean` Boolean. `0`, `&`, or `%.y` are true, and `1`, `|`, and `%.n` are false. Note 1 is false and 0 is true. This is sometimes referred to as "loobean". #### Source ```hoon +$ bean ? ``` #### Examples ``` > *bean %.y ``` ``` > `bean`& %.y ``` ``` > `bean`| %.n ``` *** ## `$flag` Boolean. Same as [`$bean`](#bean). #### Source ```hoon +$ flag ? ``` *** ## `$char` Character. A single `@t` character. #### Source ```hoon +$ char @t ``` #### Examples ``` > *char '' ``` ``` > `char`'a' 'a' ``` *** ## `$cord` UTF-8 text. One of Hoon's two string types (the other being `$tape`). A cord is an `$atom` of UTF-8 text. #### Source ```hoon +$ cord @t ``` #### Examples ``` > *cord '' ``` ``` > `@ux`'foobar' 0x7261.626f.6f66 ``` ``` > `@t`97 'a' ``` ``` > `@`'urbit' 499.984.265.845 ``` ``` > `@t`499.984.265.845 'urbit' ``` #### Discussion Aura `@t` designates a Unicode `$atom`, little-endian: the first character in the text is the least-significant byte. [`+trip`](/hoon/stdlib/4b.md#trip) converts from `$cord` to `$tape`, and [`+crip`](/hoon/stdlib/4b.md#crip) converts from `$tape` to `$cord`. *** ## `$byts` Bytes, least-significant first. An `$atom` `.dat` with its byte-length specified in `.wid`. This is to handle leading zeros that are typically ignored. #### Source ```hoon +$ byts [wid=@ud dat=@] ``` #### Examples ``` > *byts [wid=0 dat=0] ``` ``` > =a `byts`[4 2] > a [wid=4 dat=2] > `@ux`(rev 3 a) 0x200.0000 ``` *** ## `$date` Parsed date. A boolean designating AD or BC, a year `$atom`, a month `$atom`, and a `$tarp`, which is a day `$atom` and a time. #### Source ```hoon +$ date [[a=? y=@ud] m=@ud t=tarp] ``` #### Examples ``` > *date [[a=%.y y=0] m=0 t=[d=0 h=0 m=0 s=0 f=~]] ``` ``` > `date`(yore ~2014.6.6..21.09.15..0a16) [[a=%.y y=2.014] m=6 t=[d=6 h=21 m=9 s=15 f=~[0xa16]]] ``` ``` > now ~2018.5.25..17.55.15..9ad8 ``` #### Discussion See also: [`+year`](/hoon/stdlib/3c.md#year), [`+yore`](/hoon/stdlib/3c.md#yore) *** ## `$knot` URL-safe path element text. An `$atom` type that only permits lower-case letters, numbers, and four special characters: hyphen, tilde, underscore and period. #### Source ```hoon +$ knot @ta ``` #### Examples ``` > *knot ~. ``` ``` > `@ta`105 ~.i ``` *** ## `$noun` Any `$noun`. #### Source ```hoon +$ noun * ``` #### Examples ``` > *noun 0 ``` ``` > `noun`'foo' 7.303.014 ``` ``` > `noun`"foo" [102 111 111 0] ``` *** ## `$path` Like a Unix path. A path is a list of [`$knot`](#knot). #### Source ```hoon +$ path (list knot) ``` #### Examples ``` > *path / ``` ``` > `path`"foo" /f/o/o ``` ``` > `path`[~.foo ~.bar ~.baz ~] /foo/bar/baz ``` *** ## `$stud` Standard name. #### Source ```hoon +$ stud :: standard name $@ mark=@tas :: auth=urbit $: auth=@tas :: standards authority type=path :: standard label == :: ``` *** ## `$tang` Bottom-first error. A list of [`$tank`](#tank)s. It's for printing types and bottom-up printing of stack traces. #### Source ```hoon +$ tang (list tank) ``` #### Examples ``` > *tang ~ ``` ``` > %- %- slog ^- tang :~ 'foo' leaf+"bar" [%palm ["|" "(" "!" ")"] leaf+"foo" leaf+"bar" leaf+"baz" ~] [%rose [" " "[" "]"] leaf+"foo" leaf+"bar" leaf+"baz" ~] == foo bar (!foo|bar|baz) [foo bar baz] ~ ~ ``` *** ## `$tank` Formatted print tree. A `$tank` is one of four cases: * Just a `$cord`. * `%leaf` is just a `$tape`. * `%palm` is a list of `$tank` delimited by the strings in `.p`, with back-steps at new lines. * `%rose` is a list of `$tank` delimited by the strings in `.p` without back-steps at new lines. #### Source ```hoon +$ tank $~ leaf/~ $@ cord $% [%leaf p=tape] [%palm p=(qual tape tape tape tape) q=(list tank)] [%rose p=(trel tape tape tape) q=(list tank)] == ``` #### Examples ``` > *tank [%leaf p=""] ``` ``` > ~(ram re 'foobar') "foobar" ``` ``` > ~(ram re leaf+"foo") "foo" ``` ``` > ~(ram re [%palm ["|" "(" "!" ")"] leaf+"foo" leaf+"bar" leaf+"baz" ~]) "(!foo|bar|baz)" ``` ``` > ~(ram re [%rose [" " "[" "]"] leaf+"foo" leaf+"bar" leaf+"baz" ~]) "[foo bar baz]" ``` *** ## `$tape` List of characters. One of Hoon's two string types, the other being [`+cord`](#cord). A tape is a list of `@tD`. #### Source ```hoon +$ tape (list @tD) ``` #### Examples ``` > *tape "" ``` ``` > `tape`"foobar" "foobar" ``` ``` > `(list @t)`"foobar" <|f o o b a r|> ``` ``` > `(list @tD)`"foobar" "foobar" ``` ``` > `(list @)`"foobar" ~[102 111 111 98 97 114] ``` *** ## `$tour` UTF-32 clusters. A `$tour` is a list of UTF-32 characters. #### Source ```hoon +$ tour (list @c) ``` #### Examples ``` > *tour ~ ``` ``` > `tour`(tuba "foobar") ~[~-f ~-o ~-o ~-b ~-a ~-r] ``` *** ## `$tarp` Parsed time. The time component of a `$date`: day, hour, minute, second and a list of `@ux` for precision. #### Source ```hoon +$ tarp [d=@ud h=@ud m=@ud s=@ud f=(list @ux)] ``` #### Examples ``` > *tarp [d=0 h=0 m=0 s=0 f=~] ``` ``` > (yell now) [d=106.751.991.821.625 h=22 m=58 s=10 f=~[0x44ff]] ``` ``` > `tarp`(yell ~2014.6.6..21.09.15..0a16) [d=106.751.991.820.172 h=21 m=9 s=15 f=~[0xa16]] ``` ``` > (yell ~d20) [d=20 h=0 m=0 s=0 f=~] ``` *** ## `$term` Hoon constant. A restricted text `$atom` for Hoon constants. The only characters permitted are lowercase ASCII letters, `-`, and `0-9`, the latter two of which cannot be the first character. The syntax for `@tas` is the text itself, always preceded by `%`. The empty `@tas` has a special syntax, `$`. #### Source ```hoon +$ term @tas ``` #### Examples ``` > *term %$ ``` ``` > *%term %term ``` ``` > %dead-fish9 %dead-fish9 ``` ``` > -:!>(%dead-fish9) #t/%dead-fish9 ``` ``` > -:!>(`@tas`%dead-fish9) #t/@tas ``` *** ## `$wain` List of strings. A list of `$cord`s. A `$wain` is used instead of a single `$cord` with `\n`. #### Source ```hoon +$ wain (list cord) ``` #### Examples ``` > *wain <||> ``` ``` > `wain`/som/del/rok <|som del rok|> ``` *** ## `$wall` List of list of characters. A list of `$tape`s. `+wall` is used instead of a single `$tape` with `\n`. #### Source ```hoon +$ wall (list tape) ``` #### Examples ``` > *wall <<>> ``` ``` > `wall`(wash [0 20] leaf+<(bex 256)>) <<"115.792.089.237.316.195.423.570.985.008.687.907.853.269.984.665.640.564.039.457.584.007.913.129.639.936">> ``` *** --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.urbit.org/hoon/stdlib/2q.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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