[Haskell-cafe] Why does this result in a runtime loop instead of a type error or typechecker loop?

λ. :set -XFlexibleContexts -XFlexibleInstances -XMultiParamTypeClasses -XUndecidableInstances λ. import RIO λ. import Data.Has λ. class HasBool a where boolL :: Lens' a Bool λ. instance {-#OVERLAPPABLE#-} HasBool a => Has Bool a where hasLens = boolL λ. instance {-#OVERLAPPABLE#-} Has Bool a => HasBool a where boolL = hasLens λ. runRIO () $ view boolL ^CInterrupted. The RIO environment () doesn't contain a Bool. I can see how the typechecker might get lost in this, but I can compile an equivalent program; it loops on execution.