Hi, With a type-class maybe? class Foo a where   foo :: Ptr a -> IO r -- not sure what is your `r` instance Foo Word16 where foo = c'foo_uint16_t instance Foo Word32 where foo = c'foo_uint32_t Sylvain On 27/10/2021 11:18, PICCA Frederic-Emmanuel wrote:

Hello, I have a bunch of C method that I need to call like this

c'foo_unit16_t :: Ptr Word16 -> IO r c'foo_uint32_t :: Ptr Word32 -> IO r ...

These methodes are called from a method like this

process :: NativeType t => Dataframe t => IO r process df = do ... <pseudo code> case typeof t of WORD16 -> c'foo_unit16_t ... WORD32 -> c'foo_uint32_t ...

Since there is type erasure, I would like to know what is the best way to write this process method.

thanks for you help

Frederic _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.