Maybe some pseudo code would make understanding your problem easier?
On Sat, 2015-05-02 at 10:34, Marcus Appelros <[email protected]> wrote:
> This is the use case: abstract Component with a getargs(c::Component) that
> returns an array with the fields of components, for concreteness lets say a
> Der type with the fields x and dy. We want to be able to fetch the fields,
> mutate the array (say replace all :a with :b^2) and then return a mutated
> immutable instance, and we want it defined generally on Component so no
> inner constructors. How?
