Arrays & Higher-Order Functions

# Array initialization
let list = [10, 20, 30]

# Adding and removing elements
list.append(40)         # [10, 20, 30, 40]
list.insert(1, 15)      # [10, 15, 20, 30, 40]
let last = list.pop()   # last is 40, list is [10, 15, 20, 30]
list.remove(15)         # removes value 15 => [10, 20, 30]

# Element update & arithmetic
list[0] += 5            # list[0] is now 15

let numbers = [1, 2, 3, 4, 5, 6]

# 1. map — transform each element
let doubled = numbers.map(fn(x) => x * 2)
# => [2, 4, 6, 8, 10, 12]

# 2. filter — select matching elements
let evens = numbers.filter(fn(x) => x % 2 == 0)
# => [2, 4, 6]

# 3. reduce — aggregate array into a single accumulator
let sum = numbers.reduce(fn(acc, x) => acc + x, 0)
# => 21

# 4. Method Chaining
let chainedResult = numbers
    .filter(fn(x) => x > 2)
    .map(fn(x) => x * 10)
    .reduce(fn(acc, x) => acc + x, 0)

print("Chained result: ${chainedResult}") # => 180

let users = [
    {"name": "Alice", "age": 22},
    {"name": "Bob", "age": 17},
    {"name": "Charlie", "age": 30}
]

# find — returns the first item matching predicate
let adult = users.find(fn(u) => u["age"] >= 18)
print("First adult: ${adult["name"]}") # => Alice

# every — checks if all items satisfy condition
let allAdults = users.every(fn(u) => u["age"] >= 18)
print("All adults? ${allAdults}") # => False

# some — checks if any item satisfies condition
let hasMinor = users.some(fn(u) => u["age"] < 18)
print("Has minor? ${hasMinor}") # => True

let scores = [10, 5, 20, 15, 10]

print("sum: ${scores.sum()}")       # => 60
print("max: ${scores.max()}")       # => 20
print("min: ${scores.min()}")       # => 5
print("unique: ${scores.unique()}") # => [10, 5, 20, 15]

# In-place sorting and non-destructive sorted()
let letters = ["c", "a", "b"]
print(letters.sorted())             # => ["a", "b", "c"]