Value types in the dabric prelude

2022-02-03

first order types

• unsigned integer: little endian integer of a fixed byte count. Supported byte sizes are 1,2,4,8. Note that the byte size is not a type parameter but the regular type size value given for every type.
• signed integer: twos complement liitle endian integer. Supported byte sizes are 1,2,4,8
• unsigned leb128: a leb128 encoded unsigned integer
• string: utf-8 encoded byte size prefixed string
• type tagged value: a type tag / value -pair where the type tag is a VQL refering to the value type sequence in the file header

higher order types

• array: a byte size prefixed sequence of values of a single type
• type tagged array: a byte size prefixed sequence of type tagged values
• tuple: fixed length sequence of fixed type values. Tuple type is parameterized with an array of types.
• struct: fixed length sequence of attribute values. Structs type parameters are a sequence of attribute id / type -pairs. See length vs size.
• record: a byte size prefixed sequence of attribute entity id, type tag, value triplets. See struct vs record.
• type alias: a type definition along with an entity id that defines the meaning of the values. For example entity id (array of unsigned leb128:s), date (struct of year, month and day).

named value type instances

Named value type instance is a value type that is parameterized with a type name as entity id and a value type reference and it's parameters.

Examples:

• entity id: a type alias for an array of VLQ:s where the first VLQ refers to a stream id in the file header
• epoch: a unix epoch as an unsigned leb128

value attributes

Dabric prelude defines the following attributes to be used in structs and records:

• date time
• year
• month
• day
• hour
• minute
• second
• millisecond

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