Oh i see so the only simple option would be to add something along the line `drop(map, a) when is_atom(a)` but it would mean making the widening the api surface. Maybe the answer does not lie directly in elixir core but in something that would run after the elixir compiler able to give suggestions about the errors ? It clearly is not the scope of the discussion but I would be interested to know what you think about it and what elixir api could be used to make such a hint/suggestion layer.
On Saturday, January 12, 2019 at 8:38:20 PM UTC+1, Andrea Leopardi wrote: > > The problem here is that Map.drop/2 expects a term as the second argument > that implements the Enumerable protocol. This means that realistically we > can't check for a specifically supported data type or types, since anything > could implement the Enumerable protocol. For example, I might implement > Enumerable for atoms and then your code would work. > > On Sat, 12 Jan 2019 at 19:10, Edouard Mnd <[email protected] > <javascript:>> wrote: > >> Hi, >> >> I have been running into the same issue again and again with elixir where >> I get a weird error like >> >>> (Protocol.UndefinedError) protocol Enumerable not implemented for "foo". >>> This protocol is implemented for: DBConnection.PrepareStream, DBCo >>> nnection.Stream, Date.Range, Ecto.Adapters.SQL.Stream, File.Stream, >>> Function, GenEvent.Stream, HashDict, HashSet, IO.Stream, List, Map, MapSet, >>> Postgr ex.Stream, Range, Stream, StreamData, Timex.Interval >>> >> when doing `Map.drop(foo, :sth). >> Obviously i'm doing something wrong : I should give a list as a second >> argument but I keep forgetting and I bet i'm not the only one. >> My proposal would consist in handling this case explicitly either by >> allowing for such a case to work or giving back a clear error message such >> as "Are you trying to do Map.drop(foo,[:sth]) ?". >> I'm greatly inspired by the rust language in asking this, indeed rust >> gives you really great error messages when doing silly things. >> >> I hope you find my proposal clear and interesting as it clearly is not >> just about Map.drop but also about giving better error messages to the >> developer when doing silly things which I think is important. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "elixir-lang-core" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elixir-lang-core/550f8801-c0d9-41ea-947a-8c3ee483c76a%40googlegroups.com >> >> <https://groups.google.com/d/msgid/elixir-lang-core/550f8801-c0d9-41ea-947a-8c3ee483c76a%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > -- > > Andrea Leopardi > [email protected] <javascript:> > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/93fd3c38-c285-48b8-87d1-898fe45a1afc%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
