What's the rationale behind the fact that a set is considered as :sequential ? For instance

(validate [:sequential string?] #{"aa"}) ;; false

it’s following the clojure way:

{:sequential (m/-collection-schema {:type :sequential, :pred sequential?})}

(sequential? #{}) ; => false

you should be able create custom collections types easily that access both sequentials and sets.

@ikitommi Could you share a pointer to the documentation about custom collection types?

@viebel sequential means: it has a defined order. sets are not ordered, similar to maps, although you can create sequences out of them

Yeah. It makes sense. But still surprising.

I think we need a name and a predicate for a bunch of things that could be either in a set or in a sequence

My use case is a function that receives a bunch of ids and return the entities whose id is contained in the bunch

you could always say [:or [:sequential :int] [:set :int]].

or, one could always transform the values always to sets/vectors.

coll? works as well, if you don't mind using predicates directly

(coll? {}) ;=> true

coercion is always an option:

(m/decode
 [:set :int]
 [1 2 3]
 (mt/collection-transformer))
; => #{1 2 3}

Any recommendations on how to approach extracting out a registry from a schema? For example:

[:map
  [::id int]
  [:name string?]
  [::country {:optional true} string?]]

to

{::id int?
 ::country string?}

and as a nice to have, the schema simplified to use the new registry:

[:map
  ::id
  [:name string?]
  [::country {:optional true}]]