#if __GLASGOW_HASKELL__ < 609
tryM :: IOEnv env r -> IOEnv env (Either Exception r)
#else
-tryM :: IOEnv env r -> IOEnv env (Either ErrorCall r)
+tryM :: IOEnv env r -> IOEnv env (Either IOException r)
#endif
-- Reflect UserError exceptions (only) into IOEnv monad
-- Other exceptions are not caught; they are simply propagated as exns