[ANN] SumTypes.jl v0.4

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I am curious about a usecase along the following lines, focused on still writing code as if we are using typical multiple dispatch from Julia:

Someone already has a simple ray-tracing library written in Julia which implements tens of different solid object primitives (each a separate struct with supertype Abstract3DObject). Then a render function looks something like

function render(scene::Vector{Abstract3DObject})
    for object in scene
        find_ray(object)
    ...
end

find_ray itself has a ton of methods for the various object types.

My understanding is that this is a rather bad way to do things in Julia because

  • one usually has a ton of different types stored in scene so the vector contains boxed objects even if all the objects are otherwise pretty simple
  • find_ray inside of render will be using slower dynamical dispatch because there are too many types for automatic union splitting

Can SumTypes be used here without rewriting the library to make Abstract3DObject a sumtype? Can the sumtype be created dynamically by some wrapper for the render function, so that everything except render can be written as if SumType is not involved?

I guess I am asking for a function that dynamically creates a sumtype when one of its arguments is a Vector of many structs of the same abstract type.

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