Testing performance for elixir protocol dispatch for is_record

output

R16B01 @ x86_64-apple-darwin12.4.0, 1000000 iterations
    when matching: binary is 55.46651865727732% faster
when not matching: binary is 17.42297571085909% faster
[{214705,'Foo.List'},
 {177297,'Foo.Bin'},
 {345924,'Elixir.List'},
 {154052,'Elixir.Bin'}]



R15B03 @ i386-apple-darwin10.8.0, 1000000 iterations
    when matching: binary is 29.912398410005824% faster
when not matching: binary is 4.686099611625627% faster
[{46862,'Foo.List'},
 {44666,'Foo.Bin'},
 {78994,'Elixir.List'},
 {55365,'Elixir.Bin'}]


R16B01 @ java, 1000000 iterations
    when matching: binary is -51.698619960570305% faster
when not matching: binary is -32.230693921143974% faster
[{67414,'Foo.List'},
 {89142,'Foo.Bin'},
 {104997,'Elixir.List'},
 {159279,'Elixir.Bin'}]

test.erl

-module(test).

-export([main/0, main/1]).

main() ->
    main(1000).

main(N) ->
    T1 = {ListNo,_} = timer:tc(fun test_list/2, ['Foo.List', N]),
    T2 = {BinNo,_} = timer:tc(fun test_bin/2, ['Foo.Bin', N]),
    T3 = {ListOk,_} = timer:tc(fun test_list/2, ['Elixir.List', N]),
    T4 = {BinOk,_} = timer:tc(fun test_bin/2, ['Elixir.Bin', N]),

    io:format("~s @ ~s, ~p iterations~n",
              [erlang:system_info(otp_release),
               erlang:system_info(system_architecture),
               N]),

    io:format("    when matching: binary is ~p% faster~n", [ 100 * ( 1.0 - (BinOk / ListOk)) ]),
    io:format("when not matching: binary is ~p% faster~n", [ 100 * ( 1.0 - (BinNo / ListNo)) ]),

    [T1,T2,T3,T4].


test_list(Atom, 0) ->
    Atom;
test_list(Atom, N) ->
    case atom_to_list(Atom) of
        "Elixir." ++ _ ->
            test_list(Atom, N-1);
        _ ->
            test_list(Atom, N-1)
    end.


test_bin(Atom, 0) ->
    Atom;
test_bin(Atom, N) ->
    case atom_to_binary(Atom, latin1) of
        <<"Elixir.", _/binary>> ->
            test_bin(Atom, N-1);
        _ ->
            test_bin(Atom, N-1)
    end.