Finding a value in {key, value} list in Erlang

Question

I'm new to Erlang and maybe I just missed this issue in the tutorial though it is trivial. Let's say, I have a list of {Key, Value} pairs gotten from erlang:fun_info/1. I want to know function arity, the rest of the list is no interest to me. So I write something like:

find_value( _, [] ) ->
    nothing;
find_value( Key, [{Key, Value} | _] ) ->
    Value;
find_value( Key, [_ | T] ) ->
    find_value( Key, T).    

And then do:

find_value( arity, erlang:fun_info( F )).

I works fine, but should something like find_value be a too common routine to write it? I failed to find its' analogue in BIFs though. So the question is: it there a nice elegant way to get a value for a key from a list of {key, value} tuples?

Answer 1

The module proplists contains get_value/2, which should be what you want.

Answer 2

lists:keyfind/3 does this. Here I've mapped it into your find_value/2 interface:

find_value(Key, List) ->
    case lists:keyfind(Key, 1, List) of
        {Key, Result} -> Result;
        false -> nothing
    end.

proplists may be an even better route, though.