Closures & Lexical Scoping

Understand how enclosed environments and lexical variable capture work in NouvaLang runtime.

1. Lexical Block Scoping

Variables declared inside a block (such as inside an if statement, loop, or function) are scoped exclusively to that block and its child environments:

let global_message: str = "Outer";

if true {
    let inner_message: str = "Inner";
    print(global_message); // Accessible: "Outer"
    print(inner_message);  // Accessible: "Inner"
}

// Accessing inner_message here will result in an Undefined variable error

2. Environment Enclosure & First-Class Functions

When a function is created, it retains a reference to its enclosing lexical environment:

let base_multiplier: int = 10;

fun scale(factor: int) -> int {
    return factor * base_multiplier; // Captures base_multiplier
}

print(scale(5)); // 50