Functions & Closures
Functions in Djazair are first-class citizens. They can be stored in variables, passed as arguments, returned from other functions, and capture lexical closures.
Defining Functions
djazair
# Standard function declaration
fn add(a, b)
return a + b
end
print(add(10, 20)) # => 30
# Concise Arrow Function expression
let multiply = fn(a, b) => a * b
print(multiply(4, 5)) # => 20Default Arguments
Parameters can have default expressions, which can even reference previous parameters:
djazair
fn greet(name = "World", greeting = "Hello")
print("${greeting}, ${name}!")
end
greet() # => Hello, World!
greet("Riad") # => Hello, Riad!
greet("Ali", "Welcome") # => Welcome, Ali!
# Referencing earlier parameters in default values:
fn calculateOffset(base, step = base * 2)
return base + step
end
print(calculateOffset(5)) # => 15 (5 + 10)Rest Parameters (...args)
Variadic functions accept any number of trailing arguments packed into an Array:
djazair
fn sumAll(initial, ...rest)
let total = initial
for val in rest
total += val
end
return total
end
print(sumAll(10, 1, 2, 3, 4)) # => 20Lexical Closures
Functions maintain a reference to their enclosing scope even after the outer function has returned:
djazair
fn createCounter(start = 0)
let count = start
return fn()
count++
return count
end
end
let c1 = createCounter(10)
print(c1()) # => 11
print(c1()) # => 12
let c2 = createCounter(100)
print(c2()) # => 101 (independent closure environment)