I just read the Wikipedia article about the Grover algorithm and decided to have some fun by trying to implement it in Q#.
I may not be entirely correct and I did this just to practice some Q#.
dotnet run
Grover's algorithm is a quantum algorithm that can search an unsorted database (or an arbitrary list of N elements) in √N steps, which is a significant improvement over classical algorithms which, on average, need N/2 steps.
This is not a data type, it just means that the operation doesn't have a return value.