Why Curry and partial application in Ruby? - Purpose & Use Cases

The Big Idea

What if you could create many custom methods from one, without rewriting code every time?

The Scenario

Imagine you have a method that adds three numbers, and you need to use it many times with some numbers fixed but others changing.

Without special tools, you write many similar methods or repeat code to handle each case.

The Problem

This manual way is slow and boring because you rewrite similar code again and again.

It's easy to make mistakes and hard to change later.

The Solution

Curry and partial application let you fix some inputs of a method and create new simpler methods automatically.

This saves time, reduces errors, and makes your code cleaner and easier to understand.

Before vs After

✗ Before

def add(a, b, c)
  a + b + c
end

add(1, 2, 3)
add(1, 2, 4)

✓ After

add = ->(a, b, c) { a + b + c }
add_curried = add.curry
add_one_two = add_curried.call(1).call(2)
add_one_two.call(3)
add_one_two.call(4)

What It Enables

You can create many customized versions of a method quickly, making your programs flexible and easy to maintain.

Real Life Example

Think of a coffee shop where you always order a coffee with milk and sugar, but sometimes change the size.

Partial application lets you fix milk and sugar once, then quickly choose the size each time.

Key Takeaways

Manual repetition is slow and error-prone.

Curry and partial application fix some inputs to create new simpler methods.

This makes code cleaner, faster to write, and easier to change.