Congratulations
Congratulations for making it this far! You have learned how to boost your productivity using Vala in various situations. While the current state of the language itself is pretty stable, the reference implementation for the compiler still has a way to go. You can easily force the compiler to choke on some code pieces—in particular when combining generics, arrays, and delegates.
On the road to version 1.0, this will all hopefully be fixed in the future.