Use typed fields in models

[goerz]

Antique.jl/src/HydrogenAtom.jl

Lines 4 to 10 in ad463ca

	@kwdef struct HydrogenAtom
	Z = 1
	mₑ = 1.0
	a₀ = 1.0
	Eₕ = 1.0
	ℏ = 1.0
	end

has all fields in the HydrogenAtom types as Any. Even if you don't care about performance, this is not a good idea:

julia> HA = HydrogenAtom(Z="1")
Antique.HydrogenAtom(Z=1, mₑ=1.0, a₀=1.0, Eₕ=1.0, ħ=1.0)

julia> E(HA)
ERROR: MethodError: no method matching -(::String)

My recommendations would be the proof-of-concept implementation

If you want to support both a full ASCII and a Unicode API, then I don't think you can use @kwdef. If you stick to ASCII (which I might, at the end of the day, just because it put so much less demand on contributors of new models), and @kwdef is probably possible.

This applies to all models, obviously, not just HydrogenAtom

Ref. openjournals/joss-reviews#8545 (comment)