Extract function from function type

General Usage
,
5

As I said in the linked discussion though, if you want to ignore those corner cases, you can write something like

function default(::Type{ft}) where {ft <: Function}
    if isdefined(ft, :instance)
        ft.instance
    else 
        error("This type does not have a single instance")
    end
end

which will work for most functions, but can definitely fail for the reasons I’ve described.