Code:

{
	in := map[string]interface{}{"foo": 1, "hello": "world"}
	b, err := msgpack.Marshal(in)
	_ = err

	var out map[string]interface{}
	err = msgpack.Unmarshal(b, &out)

	var outKeys []string
	for k := range out {
		outKeys = append(outKeys, k)
	}
	sort.Strings(outKeys)

	fmt.Printf("err: %v\n", err)

	for _, k := range outKeys {
		fmt.Printf("out[\"%v\"]: %#v\n", k, out[k])
	}

	// Output: err: <nil>
	// out["foo"]: 1
	// out["hello"]: "world"
}

Output:

err: <nil>
out["foo"]: 1
out["hello"]: "world"

Code:

{
	buf := &bytes.Buffer{}

	enc := msgpack.NewEncoder(buf)
	in := map[string]interface{}{"foo": map[string]interface{}{"hello": "world"}}
	_ = enc.Encode(in)

	dec := msgpack.NewDecoder(buf)
	dec.DecodeMapFunc = func(d *msgpack.Decoder) (interface{}, error) {
		n, err := d.DecodeMapLen()
		if err != nil {
			return nil, err
		}

		m := make(map[string]interface{}, n)
		for i := 0; i < n; i++ {
			mk, err := d.DecodeString()
			if err != nil {
				return nil, err
			}

			mv, err := d.DecodeInterface()
			if err != nil {
				return nil, err
			}

			m[mk] = mv
		}
		return m, nil
	}
	out, err := dec.DecodeInterface()
	fmt.Printf("%v %#v\n", err, out)
	// Output: <nil> map[string]interface {}{"foo":map[string]interface {}{"hello":"world"}}
}

Output:

<nil> map[string]interface {}{"foo":map[string]interface {}{"hello":"world"}}

Code:

{
	b, err := msgpack.Marshal(true)
	fmt.Printf("%v %#v\n", err, b)
	// Output: <nil> []byte{0xc3}
}

Output:

<nil> []byte{0xc3}

Code:

{
	var out bool
	err := msgpack.Unmarshal([]byte{0xc3}, &out)
	fmt.Println(err, out)
	// Output: <nil> true
}

Output:

<nil> true