What is Functional Programming in TypeScript?
October 27, 2023
A function is pure if:
- It returns the same output for the same input.
- It has no side effects.
In FP, once data is created, it cannot be changed. Instead of modifying data, we produce a new copy of the data with modifications.
Example using TypeScript with arrays:
First-Class and Higher-Order Functions
In TypeScript, functions are first-class citizens, meaning they can be passed as arguments, returned as values, and assigned to variables.
A higher-order function either:
- Takes one or more functions as arguments, or
- Returns a function as its result.
Currying is a technique in which a function that takes multiple arguments is transformed into a sequence of functions that each take a single argument.
Function composition is the process of combining two or more functions to produce a new function. It's a way to create complex functions by chaining together simpler ones.
Functors and Monads
While these concepts originate from category theory, they're crucial in the realm of functional programming.
- Functor: An object that has a
- Monad: An object with
In TypeScript, arrays can be considered functors:
Promises in TypeScript can be seen as monads:
This guide introduces the basic principles of functional programming in TypeScript. By incorporating these principles, you can write cleaner, more maintainable, and more predictable code. Remember, functional programming is not just about following a set of rules, but also about adopting a mindset to solve problems in a different way.
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