Variable

Theory

A variable in Arch is a reference to a space specified by a type expression. This type expression may be a simple type (such as Int, String), or a dependent type that refers to other variables (for example a structure).

Variables in Arch are always associated with a type, ensuring type safety and clarity in all expressions. Each variable represents a name that refers to a unique location, whose possible values are determined by its type.

Syntax

Define a variable:

<identifier>: <TypeExpression>

<identifier> is the name of the variable.

<TypeExpression> can be a simple type, or a dependent type (e.g., a structure).

Assign an inhabitant to the variable:

<identifier> = <expression>

<expression> must produce a value (inhabitant) of the type specified for <identifier>.

Define and assign a variable in one statement:

<identifier>: <TypeExpression> = <expression>

Example

x: Int
y = 10          # auto type inference
z: Int = 10