Java – type prompt functions in clojure

I tried to solve the reflection warning in clojure, which seems to be due to the lack of type inference for the function return value of ordinary Java objects

Simple example code that demonstrates the problem:

(set! *warn-on-reflection* true)    

(defn foo [#^Integer x] (+ 3 x))

(.equals (foo 2) (foo 2))

=> Reflection warning,NO_SOURCE_PATH:10 - call to equals can't be resolved.
   true

What is the best solution? Can this be done with type hints?

Solution

Both versions seem to work:

user> (defn foo [^Integer x] (+ 3 x))
#'user/foo
user> (.equals (foo 2) (foo 2))
Reflection warning,NO_SOURCE_FILE:1 - call to equals can't be resolved.  ;'
true
user> (.equals ^Integer (foo 2) ^Integer (foo 2))
true
user> (defn ^Integer foo [^Integer x] (+ 3 x))
#'user/foo
user> (.equals (foo 2) (foo 2))
true

Please note that clojure's type hint still has some limitations in version 1.2, so this may never be the same Also note that ^ ^ does not approve of the use of ^