array_transformations.tg

// array_transformations.tg - Array Transformation Methods in TargaScript
//
// This example demonstrates how to use the built-in methods for
// transforming arrays: map, filter, and reduce.

// ======================================================================
// Map Method
// ======================================================================
// The map method applies a transformation to each element in an array
// and returns a new array with the transformed values.
// Syntax: array.map(function)

print("=== Map Method Examples ===")

// Example 1: Squaring numbers
let numbers = range(1, 5)
print("Original numbers:", numbers)

// Using anonymous function for transformation
let squared = numbers.map(fn(num) {
  return num * num
})
print("Squared numbers:", squared)

// Example 2: Converting strings to uppercase
let names = ["alice", "bob", "charlie", "david"]
print("Original names:", names)

let uppercase = names.map(fn(name) {
  return name.upper()
})
print("Uppercase names:", uppercase)

// Example 3: Adding a prefix to each name
let prefixed = names.map(fn(name) {
  return "user_" + name
})
print("Names with prefix:", prefixed)

// ======================================================================
// Filter Method
// ======================================================================
// The filter method creates a new array with elements that pass a test
// implemented by the provided function.
// Syntax: array.filter(function)

print("=== Filter Method Examples ===")

// Example 1: Filtering even numbers
let mixed_numbers = range(1, 10)
print("Original numbers:", mixed_numbers)

let even_numbers = mixed_numbers.filter(fn(num) {
  return num % 2 == 0
})
print("Even numbers only:", even_numbers)

// Example 2: Filtering by string length
print("Original names:", names)
let long_names = names.filter(fn(name) {
  return name.length > 4
})
print("Names longer than 4 characters:", long_names)

// Example 3: Compound filtering
let special_numbers = mixed_numbers.filter(fn(num) {
  return (num > 3) && (num < 8)
})
print("Numbers between 3 and 8:", special_numbers)

// ======================================================================
// Reduce Method
// ======================================================================
// The reduce method applies a function against an accumulator and each
// element in the array to reduce it to a single value.
// Syntax: array.reduce(function, initial_value)

print("=== Reduce Method Examples ===")

// Example 1: Sum of numbers
print("Numbers:", mixed_numbers)
let sum = mixed_numbers.reduce(fn(acc, num) {
  return acc + num
}, 0)
print("Sum of all numbers:", sum)

// Example 2: Finding maximum value
let max_val = mixed_numbers.reduce(fn(acc, num) {
  if (num > acc) {
    return num
  }
  return acc
}, mixed_numbers[0])
print("Maximum value:", max_val)

// Example 3: Joining strings
print("Names:", names)
let joined = names.join(", ")
print("Joined names:", joined)

// ======================================================================
// Chaining Transformations
// ======================================================================
// You can chain multiple array methods to create complex
// data processing pipelines.

print("=== Chained Transformations ===")

// Example: Square numbers, filter those greater than 20, then sum them
let original = range(1, 10)
print("Original numbers:", original)

// One-line method chaining
let result = original
  .map(fn(x) { return x * x })
  .filter(fn(x) { return x > 20 })
  .reduce(fn(acc, x) { return acc + x }, 0)

print("Final result from chained operations:", result)

// For clarity, we can also see each step:
// Step 1: Square the numbers
let squares = original.map(fn(x) { return x * x })
print("After map (squares):", squares)

// Step 2: Filter squares > 20
let filtered = squares.filter(fn(x) { return x > 20 })
print("After filter (> 20):", filtered)

// Step 3: Sum the remaining values
let total = filtered.reduce(fn(acc, x) { return acc + x }, 0)
print("After reduce (sum):", total)