What are currying, partial application, and function composition in JavaScript — how do you implement curry and pipe, and where do these patterns genuinely improve production code?

Imagine you have a big Lego set with instructions. Currying is like building one step at a time: first you pick the wheels, then the body, then the roof. Partial application is when you already have the wheels and body, so you just need to add the roof later. Function composition is like connecting two Lego pieces together to make a bigger piece, and then using that to build something even bigger.