How to get an element from a list of pairs in Erlang

Question

I'm trying to make a function that recursively returns an element from a list of pairs. It takes two arguments, a list of pairs (an association list), and a Value, if the value matches the first element of a pair in a list, then it should return the second element of the pair. Else return an error if the value does not match. For example, searchpair([{K,V}], K). Should return V.

Here's what I've tried. Not sure how to add in the tuple and recurse on it.

   searchpair([], _) -> error;
   searchpair([[K, V] | Rest], Search) when V = Search -> K;
   searchpair([_ | Rest], Search) -> seachPair(Rest, Search).

Answer 1

You don't need a when , you can bind the K directly:

searchpair([], _) ->
    error;
searchpair([{K,V} | _Rest], K) ->
    V;
searchpair([_T | Rest], Search) ->
    searchpair(Rest, Search).

Also, a tuple is not a list. Moreover, function names are case sensitive.