GO语言学习——简单的key-valeu数据库的实现

写一个简单的key-value数据库，实现下面几个接口。

db:new() => Db.

db:destroy(Db) => ok.

db:write(Key, Element, Db) => NewDb.

db:delete(Key, Db) => NewDb.

db:read(Key, Db) =>{ok, Element} | {error, instance}.

db:match(Element, Db) => [Key1, ..., KeyN].

例子:

1> c(db).

{ok,db}

2> Db = db:new().

[]

3> Db1 = db:write(111,222, Db).

[{111,222}]

4> Db2 = db:write(333, 444, Db1).

[{333,444},{111,222}]

5> db:read(111, Db2).

{ok,222}

6> Db3 = db:write(555, 444, Db2).

[{555,444},{333,444},{111,222}]

7> db:read(ola, Db3).

{error,instance}

8> db:match(444, Db3).

[555,333]

9> Db4 = db:delete(333, Db3).

[{555,444},{111,222}]

10> db:match(444, Db4).

[555]