Consider additional checks on parameters

[lerno]

in, const, readonly => only read inout, mutable, readwrite => modified and read out, writeonly => write only initialize => always written to

The difficulty is adding the syntax in a good way.

[lerno]

Idea:

/**
 * @param f (in) - inparameter
 * @param x (inout) - modify
 * @param w (out, init) - will always initialize
 **/

[lerno]

Additional ideas: retain for escaping pointers.

[lerno]

in, out, inout are in. Retain and init are missing yet.