time-it macro

[pyx]

As inspired by @gilch in discussion here: https://github.com/hylang/hy/pull/1179

The macro:

(defmacro/g! time-it [expr &optional setup round]
  `((fn []
      (do (import [timeit [timeit :as ~g!timeit]])
      ~(when setup setup)
      (defn testee [] ~expr)
      (setv kwargs {})
      ~(when round `(assoc kwargs "number" ~round))
      (apply ~g!timeit [testee] kwargs)))))

hy 0.11.0+353.gca6fd66 using CPython(default) 3.5.2 on Linux
=> (defmacro/g! time-it [expr &optional setup round]
...   `((fn []
...       (do (import [timeit [timeit :as ~g!timeit]])
...       ~(when setup setup)
...       (defn testee [] ~expr)
...       (setv kwargs {})
...       ~(when round `(assoc kwargs "number" ~round))
...       (apply ~g!timeit [testee] kwargs)))))
=> (time-it (inc 1))
0.6166748020004889
=> (time-it (inc anwser))
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "<input>", line 1, in _hy_anon_fn_2
  File "/usr/lib64/python3.5/timeit.py", line 213, in timeit
    return Timer(stmt, setup, timer, globals).timeit(number)
  File "/usr/lib64/python3.5/timeit.py", line 178, in timeit
    timing = self.inner(it, self.timer)
  File "<timeit-src>", line 6, in inner
  File "<input>", line 1, in testee
NameError: name 'anwser' is not defined
=> (time-it (inc answer) (do (print "thinking.." (setv answer 42))))
thinking.. 42
0.641465346001496
=> (time-it (inc a) (setv a 12) 100)
6.975599899305962e-05
=> (time-it (inc 1) () 100)
6.572400161530823e-05
=> (time-it (inc 1) :round 100)  ;; works by accident, :round by itself is a valid expression
6.490799933089875e-05

Another approach is using read-str

Caveat

I've been fighting the macro system for the last hour, as we cannot use &kwargs with defmacro, so unless we use &rest and parse the argument ourselves (I have a kind-of-working prototype, but it is so ugly that I do not dare to share), the form of the macro is a bit rigid, I skipped the timer argument for simplicity's sake, and right now, one have to pass in the setup code to specify the round of iteration, see above.