type family DyPair p1 p2 q1 q2 :: DyadPair where ...

type family PpPC (pc :: PitchClass) :: ErrorMessage where ...

type family PpAcc (acc :: Accidental) :: ErrorMessage where ...

type family PpOct (oct :: OctaveNum) :: ErrorMessage where ...

type family PpPitch (p :: PitchType) :: ErrorMessage where ...

type family PpPitchPair (pp :: PitchPair) :: ErrorMessage where ...

type family PpDyadPair (dp :: DyadPair) :: ErrorMessage where ...

type family PitchError (t :: Symbol) (p :: PitchType) where ...

type family PitchPairError (t :: Symbol) (p :: PitchPair) where ...

type family MotionError (t :: Symbol) (d :: DyadPair) where ...

type family ChordError (t1 :: Symbol) (r :: RootType) (t2 :: Symbol) where ...