Concatenate lambdas with recursion

You can stack lambdas so that the output of one is the input of the next, using a simple recursive function. This creates a simple way to build one function upon another.

How to do it…

This is a short and simple recipe that uses one recursive function to do most of the work:

• We'll start by defining the concatenation function concat():

  template <typename T, typename ...Ts>
  auto concat(T t, Ts ...ts) {
      if constexpr (sizeof...(ts) > 0) {
          return [&](auto ...parameters) {
              return t(concat(ts...)(parameters...)); 
          };
      } else  {
          return t;
      }
  }

This function returns an anonymous lambda, which in turn calls the function again...