Hi Frederic, I tried writing my thoughts on your question in this gist here: https://gist.github.com/darcykimball/74dd7973b2dbad22b7091135a3b9d472. There's probably much more to it than what I wrote, but I'm figuring that stuff out the more I think about it. I'll try to add more when I'm convinced I get it. Best, Kevin On Tue, Aug 27, 2019 at 5:56 AM wrote:

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Today's Topics:

1. how to convert an array of foreignPtr a into a list of Ptr a (PICCA Frederic-Emmanuel)

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Message: 1 Date: Tue, 27 Aug 2019 07:19:25 +0000 From: PICCA Frederic-Emmanuel To: "The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell" Subject: [Haskell-beginners] how to convert an array of foreignPtr a into a list of Ptr a Message-ID: < A2A20EC3B8560D408356CAC2FC148E53016CF535AB@SUN-DAG3.synchrotron-soleil.fr>

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Hello, I am writing some code whcih use FFI.

one of my C functions has an array of pointer has imput

extern HklBinocularsCube *hkl_binoculars_cube_new(int32_t n_spaces,

const HklBinocularsSpace **spaces);

from Haskell, I have a list of ForeignPtr so my question how can I have something like withForeignPtr for an array of ForeignPtr

[ForeignPtr a] -> ([Ptr a] -> IO b) -> IO b

Thanks for your help.

Frederic

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