Investigate HaskTorch

[Mikolaj]

I assumed @hasktorch wraps the extensive PyTorch API in some very smart Haskell type-level programming.

However, @arkadiuszbicz hypothesises that HaskTorch is using not PyTorch, but a CI library Torch that does not implement backpropagation, but only some more basic building blocks, such as tensor multiplications. If so, we could try using Torch instead of hmatrix for the basic operations. Also, this would mean HaskTorch implements backpropagation and so, given that we do this in an original and probably efficient way, it would be great to compare both the method and the performance. I'm sure we could fruitfully share other kinds of experience as well.