What chromatic said.

But also, don't use MooseX::Declare unless you are willing to take on the extra burden of its (poor) error handling and extra startup/runtime overhead (much more so then vanilla Moose). MooseX::Declare is (mostly) stable, but really should only be used by people who find more value in having the syntactic sugar over performance and sane error reporting (read: I don't use it and don't allow it to be used for $work code).