[waterhouse]

Just for the record, let's count to 100 million. And add the numbers up while we're at it.

  ~ $ time (echo '(do (= n 0) (for i 1 100000000 (++ n i)) prn.n (quit))' | arc)
  Welcome to Racket v5.3.5.1.
  Use (quit) to quit, (tl) to return here after an interrupt.
  arc> 5000000050000000
  
  real	0m28.561s
  user	0m28.308s
  sys	0m0.249s
  ----
  ~ $ time (echo -e 'n=0 \ni=0 \nwhile (i <= 100000000): \n  n += i \n  i += 1 \n\nprint(n)\n' | python3.3)
  5000000050000000

  real	0m30.244s
  user	0m30.230s
  sys	0m0.013s

It would appear to be competitive with Python on my machine on this particular task. (Also you can make it faster by dropping into Racket.)

[dzderic]

A while loop and temporary mutable variables are definitely not the Pythonic way of doing this. More idiomatic:

    $ time python -c 'print sum(xrange(100000000 + 1))'
    5000000050000000
    
    real    0m1.398s
    user    0m1.383s
    sys     0m0.012s

Comparison to baseline:

    $ time (echo -e 'n=0 \ni=0 \nwhile (i <= 100000000): \n  n += i \n  i += 1 \n\nprint(n)\n' | python)
    5000000050000000
    
    real    0m33.140s
    user    0m32.939s
    sys     0m0.023s

[waterhouse]

I see. That is good to know; I merely chose mutating global variables in a loop because I knew how to do that in both languages. (I am not very familiar with Python.) That is not the idiomatic way to do it in Arc, either. I would normally use a recursive function, like this:

  arc> (time:xloop (i 0 n 0) (if (> i 100000000) n (next (+ i 1) (+ n i))))
  time: 9121 cpu: 9130 gc: 0 mem: 480  ; the times are in msec
  5000000050000000

Or perhaps a "higher-order function":

  arc> (time:sum idfn 1 100000000)
  time: 19889 cpu: 19908 gc: 0 mem: 1224
  5000000050000000

Or use a deforestation macro that I wrote, which is closest to your Python example:

  arc> (time:thunkify:reduce + (range 1 100000000))
  time: 17971 cpu: 17985 gc: 0 mem: 3592
  5000000050000000

Also, here's what you can get by dropping into Racket:

  arc> (time:$:let loop ((i 0) (n 0)) (if (> i 100000000) n (loop (+ i 1) (+ n i))))
  time: 402 cpu: 403 gc: 0 mem: 920
  5000000050000000

I suppose Python has an analogue of that--dropping into C, or at least loading C libraries. Which Racket can do too. Mmm.