Generated sets of :ref are always empty

[helins]

Sets that contains a :ref are always generated empty, for example:

(malli.gen/sample [:set
                   {:registry {::foo :int}}
                   [:ref ::foo]])

No such problem with :vector. I tried a couple other ways in my (more complex) use case but it always boils down to this fact.

[ikitommi]

:set uses different function for generating values, if you can see what is wrong in the -coll-distict-gen compared to -coll-gen, PR most welcome:

https://github.com/metosin/malli/blob/master/src/malli/generator.cljc#L49-L70

[ikitommi]

(there is a fishy if with :ref...)