Functions

Declare functions with fn:

fn add(a, b) {
    return a + b
}
 
print(add(3, 4))   # 7

Closures

Functions are first-class values. They capture their lexical scope, forming closures:

fn makeCounter(start) {
    let count = start
    fn increment() {
        count = count + 1
        return count
    }
    return increment
}
 
let counter = makeCounter(0)
print(counter())   # 1
print(counter())   # 2
print(counter())   # 3

Each call to makeCounter creates a new closure with its own count variable. The inner function increment captures and modifies the outer variable.

Higher-Order Functions

Functions can be passed as arguments and returned from other functions:

fn makeAdder(x) {
    fn add(y) {
        return x + y
    }
    return add
}
 
let add10 = makeAdder(10)
print(add10(5))    # 15
print(add10(20))   # 30

Functions

Closures

Higher-Order Functions

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