Types and Values

Types and Values

Literal values represent values directly present in source code.

Examples:

123
3.14
"hello"
true
false
null

These are represented by the Literal enum in the frontend.

At runtime, values are represented separately.

pub enum Value {
    Number(f64),
    String(String),
    Boolean(bool),
    Null,
}

For example:

let age = 23

can become:

Value::Number(23.0)

and:

let name = "Tanmoy"

becomes:

Value::String("Tanmoy")

Why separate AST literals from runtime values?

The AST describes the program. The runtime describes values while the program runs.

For example:

AST:     Literal(Number(23))
Runtime: Value::Number(23.0)

This separation becomes increasingly important as the language grows.

Potential future runtime values include:

Number
String
Boolean
Null
Array
Object
Function
NativeFunction