Hi everyone,

In a fit of madness I have found myself writing Haskell code where I 

need to implement a Storable instance. However, by virtue of not being a 

C programmer, I'm fairly lost on some of the details, especially the 

value of the sizeOf and alignment methods.

My Haskell-level record is the following:

data SignedMessage = SignedMessage

  { messageLength :: CSize

  , messageForeignPtr :: ForeignPtr CUChar

  , signatureForeignPtr :: ForeignPtr CUChar

  }

Here is the code of the Storable instance: 

https://gist.github.com/Kleidukos/31346d067f309f2a86cbd97a85c0f1e8#file-signing-hs

And so I used `hedgehog-classes` to test the Storable instance. However, 

all the tests fail with the same reason: Prelude.undefined:

https://gist.github.com/Kleidukos/31346d067f309f2a86cbd97a85c0f1e8#file-undefined_error-txt

The main problem (and that's certainly a red herring for me) is that the 

`undefined` call comes frombase:Foreign.Marshal.Array.

Which shouldn't be a problem, as it is not supposed to be evaluated!

Yet apparently it is.

If you're interested to see the full code, it's located here: 

https://github.com/haskell-cryptography/libsodium-bindings/blob/add-sel-package/sel/src/Sel/Signing.hs

I'm not sure how to proceed from here. What would be a good angle to 

approach this?

Cheers,

Hécate

-- 

Hécate ✨

🐦: @TechnoEmpress

IRC: Hecate

WWW: https://glitchbra.in

RUN: BSD

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