Add Erlang version

primes.erl

@@ -0,0 +1,28 @@
+% to run:
+% erlc primes.erl; erl -noshell -s primes main -s init stop
+
+-module(primes).
+-compile(export_all).
+
+primes(Prime, Max, Primes,Integers) when Prime > Max ->
+  lists:reverse([Prime|Primes]) ++ Integers;
+
+primes(Prime, Max, Primes, Integers) ->
+  [NewPrime|NewIntegers] = [ X || X <- Integers, X rem Prime =/= 0 ],
+  primes(NewPrime, Max, [Prime|Primes], NewIntegers).
+
+primes(N) ->
+  primes(2, round(math:sqrt(N)), [], lists:seq(3,N,2)). % skip odds
+
+print_times(T, N) ->
+  io:format("Erlang: ~p iterations in ~p seconds = ~p seconds per 30 iterations~n", [N, T, T*30.0/N]).
+
+start(T, N) ->
+  lists:foreach(
+    fun(_) ->
+      io:format("Found ~p primes~n", [length(primes(10000000))])
+    end, lists:seq(1, N)),
+  print_times((os:system_time(millisecond)-T)/1000, N).
+
+main() ->
+  start(os:system_time(millisecond), 5).