+-- widening / narrowing
+
+narrowU :: Width -> Integer -> Integer
+narrowU W8 x = fromIntegral (fromIntegral x :: Word8)
+narrowU W16 x = fromIntegral (fromIntegral x :: Word16)
+narrowU W32 x = fromIntegral (fromIntegral x :: Word32)
+narrowU W64 x = fromIntegral (fromIntegral x :: Word64)
+narrowU _ _ = panic "narrowTo"
+
+narrowS :: Width -> Integer -> Integer
+narrowS W8 x = fromIntegral (fromIntegral x :: Int8)
+narrowS W16 x = fromIntegral (fromIntegral x :: Int16)
+narrowS W32 x = fromIntegral (fromIntegral x :: Int32)
+narrowS W64 x = fromIntegral (fromIntegral x :: Int64)
+narrowS _ _ = panic "narrowTo"