erlang小函数

assq(Key, List) ->

    case lists:keysearch(Key, 1, List) of

{value, {Key, Val}} -> {value, Val};

_ -> false

    end.

    

get_option(Key, Options) ->

    case lists:keysearch(Key, 1, Options) of

{value, {_Key, Value}} -> 

        Value;

_ ->

   throw({error, {not_found, Key}})

    end.

get_option(Key, Options, Default) ->

    case lists:keysearch(Key, 1, Options) of

{value, {_Key, Value}} -> 

   Value;

_ -> 

   Default

    end.

set_option(Key, Val, Opts) ->

    keyreplaceadd(Key, 1, Opts, {Key, Val}).

keyreplaceadd(Key, Pos, List, New) ->

    case lists:keysearch(Key, Pos, List) of

{value, _} -> lists:keyreplace(Key, Pos, List, New);

_ -> [New | List]

    end.