joshua.aug
I’m looking at an existing project with code like this:
@spec default_rating :: List.t()
@spec default_rating(non_neg_integer()) :: List.t()
def default_rating(rating_type_id \\ nil) do
{skill, uncertainty} = Openskill.rating()
rating_value = calculate_rating_value(skill, uncertainty)
leaderboard_rating = calculate_leaderboard_rating(skill, uncertainty)
%{
rating_type_id: rating_type_id,
skill: skill,
uncertainty: uncertainty,
rating_value: rating_value,
leaderboard_rating: leaderboard_rating
}
end
I don’t understand why the return type is List.t().
Can I use :: map as the return type? What’s the difference?
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fuelen
There is no such type in standard library, so the spec is invalid.
Is there a declared alias which replaces List?
slouchpie
The return type should be
map.Does this project use Dialyzer?
joshua.aug
That code is from an open source library:
teiserver/lib/teiserver/battle/libs/balance_lib.ex at master · beyond-all-reason/teiserver · GitHub
Line 421. I don’t see a declared alias that replaces List.
dimitarvp
I don’t see a declaration of the sort
@type List ...in the project so this is definitely a mistake on the authors’ part.LostKobrakai
Typespecs are not checked by compiling the code, but only by external type checkers like dialyzer and others. Therefore in a context where such checkers are not (regularly) used it‘s easy for mistakes in typespecs not to be caught.
rvirding
Yes, the code always right!
Teifion
I’m the person that wrote this. As per the other comments yes this is 100% a mistake (mine) and probably because I copied and pasted something wrong or completely misunderstood something at the time. As you can see I then changed the function and never updated the type spec which isn’t great of me.