10 Type System

10.1 Core Types

DATEX defines a range of core types, from simple primitive types such as integer and text, to more complex composite types such as Map and Set.

The term "core value" refers to a concrete instance of a core type, while "value" is used in a broader sense to denote an instance of any type.

There is no difference between primitive and composite types in their usage. Both can be accessed as references and values.

10.1.1 List of Core Types

10.1.1.1 Non-instantiable Types

Type	Description
unit	The unit type has a single value, also called unit. It is used as the return type of a function that does not return anything.
never	The never type has no values. It is used to indicate that a function does not return normally (e.g., it always throws an error).
unknown	The unknown type is the supertype of all types. It can hold any value, but values of this type cannot be used directly.

10.1.1.2 Primitive Types

Type	Variant	Example (DATEX Syntax)	Description
boolean		true / false	A boolean value can either be true or false.
null		null	A null value.
integer		42	An integer that can hold arbitrarily large finite positive and negative integer values.
	u8	42u8	An integer with a range of 0 to 255.
	u16	42u16	An integer with a range of 0 to 65,535.
	u32	42u32	An integer with a range of 0 to 4,294,967,295.
	u64	42u64	An integer with a range of 0 to 18,446,744,073,709,551,615.
	ubig	42ubig	An integer with an arbitrary large positive value.
	i8	42i8	An integer with a range of -128 to 127.
	i16	42i16	An integer with a range of -32,768 to 32,767.
	i32	42i32	An integer with a range of -2,147,483,648 to 2,147,483,647.
	i64	42i64	An integer with a range of -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
	ibig	42ibig	An integer with an arbitrary large negative or positive value.
decimal		42.0	A decimal that can hold arbitrarily large finite positive and negative decimal values with arbitrary precision. Additionally, it can hold the special values `infinity`, `-infinity ` and `nan`.
	f32	42.0f32	A 32-bit floating point number.
	f64	42.0f64	A 64-bit floating point number.
	big	42.0big	A decimal number with arbitrary precision.
amount		42m	A value consisting of an arbitrary size and precision decimal number and a (composite) SI unit or currency unit
url		https://unyt.org/	A URL.
endpoint		@example	A DATEX endpoint identifier.
	anonymous	@@123456789	An anonymous DATEX endpoint identifier.
	person	@user	A DATEX endpoint identifier representing a person.
	organisation	@+unyt	A DATEX endpoint identifier representing an organisation.
text		"Hello DATEX"	A string of text.
	plain	-	A string of the text with the mime type text/plain.
	markdown	-	A string of the text with the mime type text/markdown.
	html	-	A string of the text with the mime type text/html.
	...	-	TODO: additional text/* mime types
application		-	A binary blob with the mime type application/*.
	json	-	A binary blob with the mime type application/json.
	pdf	-	A binary blob with the mime type application/pdf.
	...	-	TODO: additional application/* mime types
audio		-	An audio file with the mime type audio/*.
	mp3	-	An audio file with the mime type audio/mpeg.
	wav	-	An audio file with the mime type audio/wav.
	...	-	TODO: additional audio/* mime types
video		-	A video file with the mime type video/*.
	mp4	-	A video file with the mime type video/mp4.
	webm	-	A video file with the mime type video/webm.
	...	-	TODO: additional video/* mime types
image		-	An image file with the mime type image/*.
	png	-	An image file with the mime type image/png.
	jpeg	-	An image file with the mime type image/jpeg.
	svg	-	An image file with the mime type image/svg+xml.
	...	-	TODO: additional image/* mime types
font		-	A font file with the mime type font/*.
	woff	-	A font file with the mime type font/woff.
	woff2	-	A font file with the mime type font/woff2.
	...	-	TODO: additional font/* mime types
model		-	A 3D model file with the mime type model/*.
	gltf	-	A 3D model file with the mime type model/gltf+json.
	glb	-	A 3D model file with the mime type model/gltf-binary.
	...	-	TODO: additional model/* mime types

10.1.1.2.1 Amounts

An amount consists of a decimal number and a unit. The unit can either be a SI unit or a currency unit.

SI Base Units

Unit	Description	Example DATEX Value	DATEX Type
m	meter	42m	amount/m
kg	kilogram	42kg	amount/kg
s	second	42s	amount/s
A	ampere	42A	amount/A
K	kelvin	42K	amount/K
mol	mole	42mol	amount/mol
cd	candela	42cd	amount/cd

Currency Units

Unit	Description	Example DATEX Value	DATEX Type
EUR	Euro	42EUR	amount/EUR
USD	US Dollar	42USD	amount/USD
GBP	British Pound	42GBP	amount/GBP
JPY	Japanese Yen	42JPY	amount/JPY
CHF	Swiss Franc	42CHF	amount/CHF
...	...	...	...

10.1.1.3 Composite Types

Type	Example (DATEX Syntax)	Description
List	(1,2,3)	A list of arbitrary values.
Array	[1,2,3]	An array of arbitrary values with a fixed length.
Map	("key": "value", (1): 2)	A map of arbitrary key-value pairs.
Struct	{name: "Alice", age: 30}	A struct with fixed named fields containing arbitrary values.
Set	Set(1,2,3)	A set of unique arbitrary values.
Function	function (x: integer) -> integer ( x * 2 ).	A pure function that returns the same output value for the same input value, without side effects.
Procedure	procedure (x: integer) -> integer ( x * 2 )	A procedure that can have side effects and does not guarantee the same output for the same input.
...	...	...

DATEX Script example (TODO move)

const a = 10; // inferred type for x is 'integer'
const b: integer/i8 = 255; // explicitly specifying type as signed 8-bit integer
const c: text/markdown = "# Markdown content";
const d = (1,2,3); // inferred type is List<integer>
const d: List<integer/i8> = (1,2,3); // Explicitly create a List containing only signed 8-bit integers
const s1 = Set (1,2,3); // creating a new value of type Set<integer> (inferred)
const s3 = Set<integer|text>(1,2,3); // creating a Set with an explicit type

Core types are available on every endpoint instance. Custom type definitions can be loaded as pointers from other endpoints.

10.2 Nominal and Structural Types

The DATEX type system provides both nominal and structural typing.

10.2.1 Type Aliases

10.3 Interfaces

Interfaces are special types that cannot be instantiated. They can contain overridable and sealed properties.

10.4 The ValueConsumer interface

The ValueConsumer<I,O> interface has a single property called handleValue. This property has to be assigned to a Function<I,O>. The function takes a value of type I as input and returns a value of type O.

10.5 The Function interface

The Function<I,O> interface implements the ValueConsumer<I,O> interface.

10.6 The SyncConsumer interface

10.7 The Instantiator interface

The Instantiator interface extends the ValueConsumer interface

10.8 The StreamConsumer interface