Re: [Haskell-cafe] Assimp FFI Library

From: Joel Burget Subject: [Haskell-cafe] Assimp FFI Library To: haskell-cafe@haskell.org Message-ID: Content-Type: text/plain; charset="iso-8859-1"

5. I've reduced a lot of boilerplate in Vec.hs by using the CPP preprocessor extension. I could reduce the boilerplate by another factor of 3 if I could recursively call templates but that's not allowed. I would like to have one template to generate both of these lines:

...

data Vec N2 Double t = Vec2D !Double !Double deriving (Show, Eq) data Vec N3 Double t = Vec3D !Double !Double !Double deriving (Show, Eq)

Notice there is an extra !Double in the second. Is there an easy way to do this? I don't know much about Template Haskell, would that work? Would it be easy?

Yes, it works, and it's pretty easy. My adaptive-tuple package, http://hackage.haskell.org/package/adaptive-tuple, provides this (as well as strict vectors up to 20 elements). Tuple is a bit of a misnomer. You'll need to download the source to get the Template Haskell splices because they aren't exported (tarball from hackage, or via http://www.tiresiaspress.us/haskell/adaptive-tuple/) John L.