No Bool and Char arrays with the CUDA backend

[mchakravarty]

The CUDA backend can currently not handle arrays that contain elements of typeBool or Char. In D.A.A.Array.Data, see the instance declarations for ArrayElem Bool and ArrayElem Char for details.

[mchakravarty]

@tmcdonell Let's get to the ground of this restriction. In the .cabal file for the CUDA backend, you wrote that this restriction is a frontend issue, but I don't think so. Bool and Char are perfectly fine in the interpreter.

Have a look at the comment in D.A.A.Array.Data (https://github.com/AccelerateHS/accelerate/blob/master/Data/Array/Accelerate/Array/Data.hs#L310 and https://github.com/AccelerateHS/accelerate/blob/master/Data/Array/Accelerate/Array/Data.hs#L327). This is all just about the ptrsOfArrayData function that is needed for the backend.

[tmcdonell]

Relevant commits:

• ed0a3d3
• AccelerateHS/accelerate-cuda@599f2cd

[mchakravarty]

Great!