The Value System

Patchwork has a simple, JSON-compatible type system. All runtime values are represented by the Value enum in crates/patchwork-eval/src/value.rs.

Value Types

#![allow(unused)]
fn main() {
pub enum Value {
    Null,
    String(String),
    Number(f64),
    Boolean(bool),
    Array(Vec<Value>),
    Object(HashMap<String, Value>),
}
}

Like JavaScript, Patchwork uses f64 for all numbers - there's no integer/float distinction.

Type Hierarchy

graph TD
    Value --> Null
    Value --> String
    Value --> Number
    Value --> Boolean
    Value --> Array
    Value --> Object
    Array -->|contains| Value
    Object -->|contains| Value

Arrays and objects can contain any value type, including nested arrays and objects.

JSON Interoperability

Values convert seamlessly to and from JSON:

#![allow(unused)]
fn main() {
// Parse JSON string into Value
let value = Value::from_json(r#"{"name": "test", "count": 42}"#)?;

// Convert Value to JSON string
let json = value.to_json();  // Pretty-printed
}

This is used by the json() and cat() builtin functions:

var data = json(read("config.json"))  // Parse file as JSON
var output = cat(data)                // Serialize back to JSON string

Type Coercion

Values support coercion to strings and booleans for use in string interpolation and conditionals.

String Coercion (to_string_value)

Boolean Coercion (to_bool)

This powers conditionals and loops:

var items = json(read("data.json"))
if items {  // truthy if non-empty array
    for var item in items {
        print(item.name)
    }
}

Implementation Notes

The Value type is designed to be:

• Clone-friendly - Values are cloned when assigned to variables
• Debug-friendly - Implements Debug for tracing
• Comparable - Implements PartialEq for equality checks

See crates/patchwork-eval/src/value.rs for the full implementation.