I’m not exactly sure I understand what you’re asking, but it looks like you’re mixing the definition of a struct with the construction of an instance of that struct.
I think what you want to do is this:
struct MyStruct
a::Int
b::String
end
const A = MyStruct(1, "value")
at the repl we see
julia> println(A.b)
value
Another thing you could do is use a NamedTuple, they’re a big like ‘anonymous structs’, e.g.
julia> const A = (;a=1, b="value")
(a = 1, b = "value")
julia> println(A.b)
value