Get the actual type from an Expr representing a type

General Usage
2

Macros work at the level of expressions and should not be messing with their meaning, e.g., care which types or values an expression represents. They can generate an expression containing an appropriate condition though:

macro my_macro(func_expr)
    func = JLFunction(func_expr)
    type_annotation_expr = func.args[1].args[2]
           
    quote 
        if $(esc(type_annotation_expr)) <: Array
            print("Got a subtype!")
            # Insert expansion suitable for subtypes here ...
        else
            # Insert alternative expansion here ...
            nothing
        end
    end
end

julia> @my_macro function f(x::Vector{Int}) end
Got a subtype!
julia> @my_macro function g(x::Real) end
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