Clojure core.typed comparator

comp.sh

;; Trying to annotate a comparator that sorts a list of namespaces alphabetically

zork-fortress.core=> (clojure.core.typed/cf (comp (t/fn [ns1 :- clojure.lang.Namespace ns2 :- clojure.lang.Namespace] :- t/Num (compare (str ns1) (str ns2)))))
Type Error (/private/var/folders/s1/t0k7x43122ggbclq88zgjl400000gn/T/form-init8319721319789341749.clj:1:24) Polymorphic function comp could not be applied to arguments:
Polymorphic Variables:
	x
	y
	b

Domains:
	(t/IFn [x -> y]) (t/IFn [b ... b -> x])

Arguments:
	(t/IFn [clojure.lang.Namespace clojure.lang.Namespace -> java.lang.Number])

Ranges:
	(t/IFn [b ... b -> y])

in: (comp (do :clojure.core.typed.special-form/special-form :clojure.core.typed/fn {:ann (quote ({:ret-type {:type t/Num}, :dom ({:type clojure.lang.Namespace} {:type clojure.lang.Namespace})}))} (fn* ([ns1 ns2] (clojure.lang.Util/compare (str ns1) (str ns2))))))

ExceptionInfo Type Checker: Found 1 error  clojure.core/ex-info (core.clj:4403)

At first glance, using comp is odd. comp is for composing functions - I think you want (partial sort (fn ...)).

But sort's going to want something that's actually an instance of java.util.Comparator.

Try this:

(ann compare-ns
  (t/I java.util.Comparator
       (t/IFn [clojure.lang.Namespace clojure.lang.Namespace -> t/Num])))

(def compare-ns
  (comparator str))

I thought (comp) was (comparator). Didn't know that latter existed. Simply switching from the former to the latter makes it validate. Thanks!