+@tyConArgVrcs_maybe@ gives a list of (occPos,occNeg) flags, one for
+each tyvar, if available. See @calcAlgTyConArgVrcs@ for how this is
+actually computed (in another file).
+
+\begin{code}
+tyConArgVrcs_maybe :: TyCon -> Maybe ArgVrcs
+
+tyConArgVrcs_maybe (FunTyCon {} ) = Just [(False,True),(True,False)]
+tyConArgVrcs_maybe (AlgTyCon {dataTyConArgVrcs = oi}) = Just oi
+tyConArgVrcs_maybe (PrimTyCon {primTyConArgVrcs = oi}) = Just oi
+tyConArgVrcs_maybe (TupleTyCon {tyConArity = arity }) = Just (replicate arity (True,False))
+tyConArgVrcs_maybe (SynTyCon {synTyConArgVrcs = oi }) = Just oi
+tyConArgVrcs_maybe _ = Nothing
+\end{code}
+