[erlang-questions] Elixir Protocols in Erlang & a Strange Warning

[José Valim]

>
> It is more verbose, but will not come at any cost in terms of genericity
> and will not mess up tracing and anything else the way parametrized
> modules used to.
>
> You are right, however, that Erlang doesn't really have a thing like
> protocols, which are a pretty neat feature in languages that can provide
> a solid implementation for them.
>

Right. The parameterized module is not related to Elixir protocols at all.
The parameterized module here doesn't offer any benefit over a direct
dispatch. As Fred said, it only messes up stacktraces and what you have at
the end is still ad-hoc polymorphism (via guards).

I want to clarify this is not how Elixir protocols work. Vincent's example
is a good approximation but we are able to optimize it quite well. Once you
build a release the cost of a protocol dispatch is quite low: it costs a
pattern match (which you would have anyway) and one extra remote call.


*José Valim*
www.plataformatec.com.br
Skype: jv.ptec
Founder and Lead Developer
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