A Context type for holding a function that will use some context to execute something analoguous to a database operation.

This is equivalent to holding something like:

 withConnection someConnection

where you have previously set up someConnection by specifying a connection string or something like that. This lets us support any kind of backend (even an in-memory Map in an IORef), and most interestingly, we can use just raw connections or a connection pool, this approach really covers a lot of situations while keeping everything quite simple.