C++17 STL Cookbook

Composing functions by concatenation

A lot of tasks are not really worthy of being implemented in completely custom code. Let's, for example, have a look on how a programmer might solve the task of finding out how many unique words a text contains with the programming language Haskell. The first line defines a function unique_words and the second one demonstrates its use with an example string:

Wow, that is short! Without explaining Haskell syntax too much, let's see what the code does. It defines the function called unique_words, which applies a series of functions to its input. It first maps all the characters from the input to lowercase ...