2.3 KiB
Types
All data presentations (nouns) of the Obelisk system available for user interaction -- whether reading, manipulation, or creation -- are strongly typed.
The fundamental data element is an atom typed by an aura. All data cells (the intersection of a table row and table column) are a typed atom. Obelisk supports the following auras:
| aura | type | representation |
|---|---|---|
| @c | unicode codepoint | ~-~45fed. |
| @da | date, absolute | ~2020.12.25..7.15.0..1ef5 |
| @dr | date, relative | ~d71.h19.m26.s24.9d55 |
| @f | loobean | %.y |
| @if | IPv4 address | .195.198.143.90 |
| @is | IPv6 address | .0.0.0.0.0.1c.c3c6.8f5a |
| @p | phonemic base | ~laszod-dozser-fosrum-fanbyr |
| @q | phonemic base, unscrambled | .~laszod-dozser-dalteb-hilsyn |
| @rh | IEEE-754 half-precision, 16-bit | .~~3.14 |
| @rs | IEEE-754 single-precision, 32-bit | .3.141592653589793 |
| @rd | IEEE-754 double-precision, 64-bit | .~3.141592653589793 |
| @rq | IEEE-754 quadruple-precision, 128-bit | .~~~3.141592653589793 |
| @s | integer, signed (sign bit low) | |
| @sb | signed binary | --0b10.0000 |
| @sd | signed decimal | --1.000 |
| @sv | signed base-32 | --0v201.4gvml.245kc |
| @sw | signed base-64 | --0w2.04AfS.G8xqc |
| @sx | signed hexadecimal | --0x2004.90fd |
| @t | UTF-8 text (cord) | 'urbit' |
| @ta | ASCII text (knot) | ~.urbit |
| @tas | ASCII text symbol (term) | %urbit |
| @ub | unsigned binary | 0b10.1011 |
| @ud | unsigned decimal | 8.675.309 |
| @uv | unsigned base-32 | 0v88nvd |
| @uw | unsigned base-64 | 0wx5~J |
| @ux | unsigned hexadecimal | 0x84.5fed |
All datasets in Obelisk are tables. All tables either are, or derive from, base-tables spawned by CREATE TABLE.
Base-table (<table>} rows have exactly one type, the table's atomic aura-typed columns in a fixed order.
<row-type> ::=
list <aura>
Each base-table is itself typed by its own definition.
<table-type> ::=
list <row-type>
Base-table definitions include a unique primary ordering of rows, hence its type. This is not the case for every other instance of table (dataset).
<table-set-type> ::=
set <row-type>
| set list <row-type>
Rows from <view>s, <common-table-expression>'s, and command output from <query>, <merge>, or any other table that is not a base-table can only have an immutable row ordering, if it was so specified. In general all these other tables have types are unions of <row-type>.