eeVarsOfTy' xs (ArrowT x t1 t2) = union x1s x2s
    where x1s = freeVarsOfTy' xs t1
          x2s = freeVarsOfTy' (x:xs) t2


--Symbols
---------------
l
freeVarsOfTy' xs (ArrowT x t1 t2) = union x1s x2s
    where x1s = freeVarsOfTy' xs t1
          x2s = freeVarsOfTy' (x:xs) t2


--Symbols
---------------
freeVarsOfTy' xs (ArrowT x t1 t2) = union x1s x2s
    where x1s = freeVarsOfTy' xs t1
          x2s = freeVarsOfTy' (x:xs) t2


--Symbols
---------------