Why Proc composition in Ruby? - Purpose & Use Cases

The Big Idea

What if you could connect small tasks like puzzle pieces to build powerful programs effortlessly?

The Scenario

Imagine you have several small tasks to do one after another, like making coffee: first boil water, then grind beans, then brew. Doing each step separately and manually every time can be tiring and confusing.

The Problem

Manually running each step means you might forget the order, repeat steps, or write the same code again and again. It's slow and easy to make mistakes, especially when tasks depend on each other.

The Solution

Proc composition lets you link small tasks into one smooth flow. You create little pieces of work (Procs) and then combine them so they run in order automatically. This saves time and keeps your code neat and clear.

Before vs After

✗ Before

step1 = ->(x) { x + 1 }
step2 = ->(x) { x * 2 }
result = step2.call(step1.call(3))

✓ After

step1 = ->(x) { x + 1 }
step2 = ->(x) { x * 2 }
combined = ->(x) { step2.call(step1.call(x)) }
result = combined.call(3)

What It Enables

It makes building complex tasks from simple parts easy and error-free, like creating a recipe that always works perfectly.

Real Life Example

In a web app, you might check user input, then clean it, then save it. Using proc composition, you can chain these steps so the input flows smoothly through all checks and changes.

Key Takeaways

Manual step-by-step code is slow and error-prone.

Proc composition links small tasks into one clear flow.

This makes code easier to write, read, and maintain.