Reflection warnings on "+" operator

[darkleaf]

operator.clj:149 recur arg for primitive local: sum is not matching primitive, had: Object, needed: long
Auto-boxing loop arg: sum

Is this patch correct?

(defoperator + [methods invoke]
  (loop [sum 0, [method & more] methods]
    ;;  (let [sum (long (+ (invoke method) sum))] 
    ;;             ^^^^
    (let [sum (+ (invoke method) sum)]
      (if (seq more)
        (recur sum more)
        sum))))

[darkleaf]

May be it should be a double?

[camsaul]

I've noticed this, but am not sure what the best way to fix it is. It seems like there are use cases where all your implementations would return integers and other cases where all your implementations would return floating-point numbers. BigIntegers or Decimals are also possibilities, so we probably don't want to second-guess those cases and convert those to Doubles.

[glchapman]

A simple way to get a boxed primitive is to use identity, for example:

  (loop [sum (identity 0), [method & more] methods]

should make the warning go away.

EDIT: in this case, probably better to use Long/valueOf for boxing.