Interesting example for multi-clause type spec in erlang dialyzer.

multiclause.erl

%% multi clause function type spec

-spec plus(integer(), float())   -> float();
          (float(),   integer()) -> float();
          (float(),   float())   -> float();
          (integer(), integer()) -> integer().
plus(A,B) ->
    A + B.

testp() ->
    {plus(1,2), plus(1.0,2.0), plus(1,2.0), plus(1.0,2)}.

%% types inferred by dialyzer:

-spec testp() -> {integer(),float(),float(),float()}.