Use Higher-Order Functions to Write More Reusable and Modular Haskell Code

Higher-order functions are a cornerstone of functional programming in Haskell, enabling you to write more expressive and reusable code.

In simple terms, a higher-order function is any function that either takes one or more functions as arguments, returns a function, or both.

This powerful concept allows you to abstract away repetitive logic and create functions that can operate on other functions.

One common example of a higher-order function in Haskell is 'map', which takes a function and a list as arguments and applies the function to each element of the list.

This allows you to operate on collections of data in a concise and reusable manner.

Similarly, 'foldr' and 'foldl' are higher-order functions that reduce a list to a single value by iterating over the list and applying a binary function.

Higher-order functions are not limited to just processing lists.

They can also be used to create complex control flows, manage state, and implement domain-specific logic.

For example, you can use higher-order functions to build function compositions or to implement pipelines of operations that transform data step by step.

To master higher-order functions, it’s essential to understand how they compose with other functional patterns such as monads and functors.

For example, the 'map' function in the 'Functor' type class is a higher-order function that operates on any type that implements 'Functor'.

By using these abstractions, you can write highly modular and composable code that is easier to maintain and extend.