Using generic and template lambdas
In the preceding recipe, we saw how to write lambda expressions and use them with standard algorithms. In C++, lambdas are basically syntactic sugar for unnamed function objects, which are classes that implement the call operator. However, just like any other function, this can be implemented generically with templates. C++14 takes advantage of this and introduces generic lambdas that do not need to specify actual types for their parameters and use the
auto specifier instead. Though not referred to with this name, generic lambdas are basically lambda templates. They are useful in cases where we want to use the same lambda but with different types of parameter. Moreover, the C++20 standard takes this a step further and supports explicitly defining template lambdas. This helps with some scenarios where generic lambdas are cumbersome.
It is recommended that you read the preceding recipe, Using lambdas with standard algorithms...