Consider replacing SpecialFunctions.jl by pure Julia alternatives

I've noticed that DualNumbers.jl checks if the function is available in SpecialFunctions.jl to wrap the definition with the Dual type. More recently, initiatives such as Bessels.jl have gained traction. They are pure Julia implementations of special functions that are faster and differentiable. What are your thoughts on replacing SpecialFunctions.jl by Bessels.jl and similar efforts to clean up the dependency tree downstream?

DualNumbers.jl is an indirect dependency of Distributions.jl which is pretty much everywhere in the ecosystem. So installing Distributions.jl nowadays comes with the downside of installing external _jll libraries and a ton of dependencies that could be avoided with Bessels.jl and friends.

I've already migrated all my packages from SpecialFunctions.jl to Bessels.jl because they provide all the bessel functions and the gamma (non-exported) functions I need without a single dependency.

cc: @heltonmc @cgeoga @oscardssmith

Start by reviewing how DualNumbers.jl detects and wraps functions from SpecialFunctions.jl, then inspect the package dependency declarations. Compare the required Bessel and gamma functionality with Bessels.jl and similar pure-Julia alternatives; done means reaching a maintainers-approved dependency plan, with compatibility and downstream impacts established.