[Haskell-cafe] type inference and FFI

[Sylvain Henry]

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
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