nfe-test.clj

(defn nfe-test []
  (try
    (let [nums (map #(Integer/parseInt %) ["1" "2" "1234123412341234"])]
      (when (every? #(< 3 %) nums)
	nums))
    (catch NumberFormatException nfe nil)))

(nfe-test) ;; throws NumberFormatException, but I would expect it to
           ;; return nil

(defn nfe-test []
  (try
    (let [nums (map #(Integer/parseInt %) ["1" "2" "1234123412341234"])]
      (when (every? #(< 3 %) nums)
    nums))
    (catch NumberFormatException nfe 42)
    (catch RuntimeException nfe nil)))

(nfe-test)

(defn nfe-test []
  (try
   (let [nums [(Integer/parseInt "1") (Integer/parseInt "2") (Integer/parseInt "1234123412341234")]]
     (when (every? #(< 3 %) (doall nums))
       nums))
   (catch NumberFormatException nfe 42)
   (catch RuntimeException nfe nil)))

(nfe-test)

lazy seq screws that exception up.

Yeah, someone on IRC helped me figure that out. It's highly non-obvious, although it makes sense once I understood it. And it also drives home why checked exceptions totally suck.