re: https://github.com/reiddraper/simple-check/issues/36, an overly-clever portable double generator (for use with https://github.com/cemerick/double-check, more efficient options are available if you're only targeting the JVM and are using simple-check)

gistfile1.clj

(def gen-double
  (gen/such-that
   identity
   (gen/fmap
    (fn [[^long s1 s2 e]]
      (let [neg? (neg? s1)
            s1 (str (Math/abs s1))
            ; this creates odd strings '1.+e5', but JDK and JS parse OK
            numstr (str (first s1) "." (subs s1 1)
                        (when (not (zero? s2)) s2)
                        "e" e)
            num #+clj (Double/parseDouble numstr) #+cljs (js/parseFloat numstr)]
        ; TODO use Number.isNaN once we're not using phantomjs for testing :-X
        (when-not (or #+cljs (js/isNaN num)
                      #+clj (Double/isNaN num)
                      #+cljs (or (== js/Infinity num) (= (- js/Infinity) num))
                      #+clj (Double/isInfinite num))
          num)))
    (gen/tuple
     ; significand, broken into 2 portions, sign on the left
     (choose -179769313 179769313) (choose 0 48623157)
     ; exponent range
     (choose -324 308)))))