Correct a runtime failure.
Correct a runtime failure.

This was EXC_BAD_ACCESSing when I used BooleanType. Since BooleanType
can be arbitrarily converted to Bool in f, I opted to just use Bool.

LlamaKit/LlamaKit,ashfurrow/LlamaKit,ashfurrow/LlamaKit,Carthage/LlamaKit,ashfurrow/LlamaKit,LlamaKit/LlamaKit,Carthage/LlamaKit,Carthage/LlamaKit,LlamaKit/LlamaKit