M-OSCAR

使用lists:keysearch函数可以方便的对一个[{key, value}, ....]列表里的指定key进行搜索，函数定义如下：

keysearch(Key, N, TupleList) -> {value, Tuple} | false
    Key = term()
    N = 1..tuple_size(Tuple)
    TupleList = [Tuple]
        Tuple = tuple()

比如说我们有这样的一个列表：

> Attributes = [{to, "jojo@verse.com"},
                {from, "oscar@verse.com/school"},
                {type, "chat"},
                {'xml:lang', "en"}].

> lists:keysearch(from, 1, Attributes).
{value, {from, "oscar@verse.com/school"}}

若指定Key不存在则返回false
> lists:keysearch(not_exist, 2, Attributes).
false