integer_coding.erl

-module(integer_coding).

-compile(export_all).

-include_lib("eqc/include/eqc.hrl").

power(_N, 0) -> 1;
power(N, P) -> N * power(N, P-1).

perturb() ->
    elements([0, 1, -1, 2, -2, 3, -3, 4, -4, 5, -5]).

sign() ->
    elements([1, -1]).

nat_power() ->
    frequency([{1, elements([27, 28, 29, 31, 32, 33, 59, 60, 61, 63, 64, 65])},
               {1, nat()}]).

interesting_int() ->
    ?LET({K, Sign, Perturb}, {nat_power(), sign(), perturb()},
      power(2, K)*Sign + Perturb).

prop_binary_iso() ->
    ?FORALL(K, interesting_int(),
            begin
                I = binary_to_integer(integer_to_binary(K)),
                I == K
            end).

prop_list_iso() ->
    ?FORALL(K, interesting_int(),
            begin
                I = list_to_integer(integer_to_list(K)),
                I == K
            end).

all() ->
    eqc:module({numtests, 3000}, ?MODULE).

t() ->
    eqc:quickcheck(eqc:testing_time(300, prop_binary_iso())).


[...]

Produces:

8> integer_coding:all().
prop_list_iso: .........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Failed! After 1498 tests.
-576460752303423488
prop_binary_iso: ...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Failed! After 588 tests.
-576460752303423488
[prop_list_iso,prop_binary_iso]
9>