> If in is an operator and overloaded by std::vector, then it's easy to implement. However, searching a `std::vector` is not really part of its implementation.

> If in is an operator and overloaded by std::vector, then it's easy to implement. However, searching a `std::vector` is not really part of its implementation. So, requiring every single range to overload an operator for trivial searching is not good, especially since there are only a few containers that have non-trivial searching. Instead, the range-based find could be specialized for containers that have non-trivial searching instead(perhaps it calls a `.find` method if available otherwise it does trivial searching). In [Linq](http://pfultz2.github.io/Linq/ http://pfultz2.github.io/Linq/), the find is specialized for mapped containers and for strings(it doesn't check for a `.find` method since that can't be done on msvc). So you can search a `std::vector` like this: std::vector<int> v = { ... }; auto it = v | linq::find(123); And you can also search the keys of a map like this: std::map<int, std::string> m = { ... }; auto it = m | linq::find(123); Plus, it has a contains function, so you can do this: if (v | linq::contains(123)) Or this: if (m | linq::contains(123)) There really is no need for a new operator just for this, since a function will suffice. However, if you really inclined to this, you could always write your own [named operator](https://github.com/klmr/named-operator)(although https://github.com/klmr/named-operator)(although I don't know if it would become standard): if (123 <in> v)