First of all, the current standard for arrays is the vector
https://hackage.haskell.org/package/vector package, array is pretty
obsolete. Secondly, are you sure you want your functions to take both
immutable and mutable arrays? You could just make them take immutable ones,
and convert using (unsafe)freeze/thaw
https://hackage.haskell.org/package/vector-0.11.0.0/docs/Data-Vector.html#g:...
beforehand.
Also, since you know that you'll only be storing Face and Vertex, you might
as well make an Unbox (or Storable) instance for them and use Unboxed (or
Storable) vectors.
Then you end up with:
import qualified Data.Vector.Unboxed as VU
data Surface = Surface { vertices :: VU.Vector Vertex, faces :: VU.Vector
Face }
render :: Surface -> IO ()
etc.
On Fri, Aug 12, 2016 at 7:12 AM, Christopher Howard
Hi. I recently learned how to use Haskell IArrays and MArrays, and they are quite convenient. I find myself often using some type of MArray for performance reasons, but also some IArray type for array data that is static in a set of computations.
Then I started wanting to use arrays inside other kinds of data types, and so quickly ran into the question: what do you do if you want a data type to contain an array, but you don't know in advance what array type you'll be working with (immutable vs. mutible, boxed vs. unboxed).
My exploration of this question led to discovering something called GADTs, which allowed me to do definitions like so
data Surface a where ISurface :: IArray a e => (a Int Vertex) -> (a Int Face) -> Surface a MSurface :: MArray a e m => (a Int Vertex) -> (a Int Face) -> Surface a
Am I heading down the right track here, or is there some better approach?
-- https://qlfiles.net My PGP public key ID is 0x340EA95A (pgp.mit.edu).
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