The weakness of success types.

discrep.erl

-module(discrep).
-export([run/0]).

% example of where type annotations fail to perform as expected.
% running `dialyzer discrep.erl` will return something similar to:
%
%   Checking whether the PLT /home/joe/.dialyzer_plt is up-to-date... yes
%   Proceeding with analysis... done in 0m0.29s
%   done (passed successfully)
%
% even though there's a type error evident by the type annotations.


run() -> some_op([]).

-spec add_one(integer()) -> integer().
add_one(Num) -> Num + 1.

-spec some_op([integer()]) -> [boolean()].
some_op(Nums) -> lists:map(fun add_one/1, Nums).