The keyvi compiler is implemented in C++11 and uses templates to allow customization, like having a different persistence layer, different minimization, etc.
The most useful customization are different value types:
Keys are always strings, values can be of any type, even nested types. Built-in types at time of writing are no-value, integer, strings and json.
Value types have to implement a "duck-type" interface.
Code: IValue_Store
In a nutshell, writing a new value store entails: serialization of the value, the interface to the compiler and the deserialization for the lookup.
Note: The compiler interface expects an ID for each unique value, the ID is used for minimization.