Iterators in Ruby — Think Less Looping, More Logic

Ruby Iterators — When Loops Just Aren’t Elegant Enough

Published: June 24, 2025 • CodeCraft Diaries #7

"If you've been writing `for` loops in Ruby like it's 1999, this one's for you."

Let’s be real: loops are the bread and butter of programming. But in Ruby? You don’t just butter the bread — you toast it, drizzle it with honey, and serve it like a gourmet dev snack.

Welcome to the elegant world of Ruby iterators — where looping is expressive, concise, and kinda beautiful.

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🚶 Why Not Just Use a Loop?

You can, of course:

for i in 1..3
  puts i
end

But Ruby gives us cooler tools. Imagine replacing that clunky loop with something like:

(1..3).each { |i| puts i }

Cleaner. Readable. Ruby-esque.

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🔄 Meet Your Iterator Friends

1. each — The Friendly Tour Guide

["coffee", "code", "chai"].each do |item|
  puts "I love #{item}"
end

Perfect for walking through arrays, hashes, or ranges.

2. map — The Transformer

numbers = [1, 2, 3]
squared = numbers.map { |n| n * n }
puts squared.inspect  # [1, 4, 9]

Pro Tip: Use map when you want to return a transformed array.

3. select — The Filter Master

scores = [10, 20, 30, 5]
high_scores = scores.select { |s| s > 15 }
puts high_scores.inspect  # [20, 30]

4. times — The Minimalist Loop

3.times { puts "Ping!" }

When all you need is repetition and vibes.

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🧠 But Wait... How Do These Work?

Under the hood, iterators work by accepting blocks of code. Like:

def custom_each(array)
  for item in array
    yield(item)
  end
end

custom_each(["a", "b"]) { |x| puts x }

That's right — iterators yield to blocks, giving you the power to inject logic right in.

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🤯 Real-World Example

Imagine you’re filtering logged-in users who are also admins:

users = [
  { name: "Alice", admin: true },
  { name: "Bob", admin: false }
]

admins = users.select { |u| u[:admin] }
puts admins.inspect

Elegant, right? No `if`, `then`, `break`, or noise.

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🚧 Common Beginner Pitfalls

• Forgetting that map returns a new array — it doesn’t modify the original.
• Using each when you really need map or select.
• Trying to return from inside a block without understanding how `yield` works.

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🧪 Mini Challenge

Write a Ruby method that accepts an array and prints only the items longer than 5 characters using select.

def long_words(words)
  long = words.select { |w| w.length > 5 }
  puts long
end

long_words(["ruby", "developer", "code", "iteration"])

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📚 Quick Recap

• each → Go through every item.
• map → Transform each item and get a new array.
• select → Filter items that match a condition.
• times → Repeat something N times.

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🔗 Related CodeCraft Diaries

• Procs and Lambdas in Ruby — The Cousins You Need to Know
• Ruby Blocks — The Secret Sauce Behind Elegant Code

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🪄 Coming Up Next

CodeCraft Diaries #8: “Modules & Mixins in Ruby — Sharing is Caring (Without the Mess)”