| > I think it would be better to focus the discussion on the question of | > whether you would ever NOT want a type constructor to be an instance | > of Typeable | | Code size? It might only be a small effect for most code, but we | occasionally see large files of automatically-generated data declarations. | | Also I rather like it that making a new data type is so cheap in terms | of code size. A single module containing "data T = A | B": | | $ size foo.o | text data bss dec hex filename | 91 32 0 123 7b foo.o | | If I add "deriving Typeable": | | text data bss dec hex filename | 587 312 0 899 383 foo.o | 7x larger! I had a look at the code, and opened two new tickets, both of which are relatively easy to deal with, if anyone would like to volunteer http://hackage.haskell.org/trac/ghc/ticket/7307 http://hackage.haskell.org/trac/ghc/ticket/7308 Simon