diff --git a/db.go b/db.go
index b869d58..cff7d1c 100755
--- a/db.go
+++ b/db.go
@@ -42,6 +42,8 @@ func New(key Type, params ...string) (db DB, err error) {
 		db, err = rclone.NewRClone(params[0], params[1])
 	case FILES:
 		db, err = NewFiles(params[0])
+	case YAML:
+		db, err = NewYaml(params[0])
 	case BOLT:
 		db, err = NewBolt(params[0])
 	case MINIO:
diff --git a/db_test.go b/db_test.go
index a30ee57..67122fe 100755
--- a/db_test.go
+++ b/db_test.go
@@ -14,6 +14,7 @@ import (
 	"strings"
 	"sync"
 	"testing"
+	"time"
 
 	"github.com/google/uuid"
 )
@@ -198,19 +199,20 @@ type = local
 	for _, db := range cases {
 		t.Run(fmt.Sprintf("%T", db), func(t *testing.T) {
 			log.Printf("Trying %T", db)
-			t.Logf("   %T: set", db)
+			t.Logf("   %T: list @[ns1, ns2] against empty", db)
 			if keys, err := db.List([]string{"ns1", "ns2"}); err != nil || len(keys) > 0 {
 				t.Errorf("%T) cannot List() empty: (%T) %+v: %v", db, err, err, keys)
 			}
-			if keys, err := db.List([]string{path.Join("ns1", "ns2")}); err != nil || len(keys) > 0 {
-				t.Errorf("%T) cannot List() empty w/ /: (%T) %+v: %v", db, err, err, keys)
-			}
+			t.Logf("   %T: set %s @[ns1, ns2]", db, validKey)
 			if err := db.Set(validKey, validValue, "ns1", "ns2"); err != nil {
 				t.Errorf("%T) cannot set: %v", db, err)
 			}
-			t.Logf("   %T: get", db)
+			t.Logf("   %T: db: %+v", db, db)
+			t.Logf("   %T: get %s @[ns1, ns2]", db, validKey)
 			if v, err := db.Get(validKey, "ns1", "ns2"); err != nil {
 				t.Errorf("%T) cannot get: %v", db, err)
+				log.Printf("%T) cannot get: %v (%+v)", db, err, db)
+				time.Sleep(time.Second * 10)
 			} else if !bytes.Equal(v, validValue) {
 				t.Errorf("%T) wrong get: %q vs %q", db, v, validValue)
 			}
diff --git a/type.go b/type.go
index b848f8e..ef4975c 100755
--- a/type.go
+++ b/type.go
@@ -21,6 +21,7 @@ const (
 	MINIO           = Type(iota)
 	RCLONE          = Type(iota)
 	MAPSTREAM       = Type(iota)
+	YAML            = Type(iota)
 )
 
 func (t Type) String() string {
@@ -37,6 +38,8 @@ func (t Type) String() string {
 		return "rclone"
 	case COCKROACH:
 		return "cockroach"
+	case YAML:
+		return "yaml"
 	case FILES:
 		return "files"
 	case BOLT:
diff --git a/yaml.go b/yaml.go
index b4c5193..2d4ccdc 100755
--- a/yaml.go
+++ b/yaml.go
@@ -2,9 +2,12 @@ package storage
 
 import (
 	"bytes"
+	"encoding/base64"
 	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
+	"local/storage/resolve"
 	"os"
 	"path"
 	"path/filepath"
@@ -43,7 +46,19 @@ func (y *Yaml) Namespaces() ([][]string, error) {
 }
 
 func (y *Yaml) List(ns []string, limits ...string) ([]string, error) {
-	return nil, errors.New("not impl")
+	namespace := resolve.Namespace(ns)
+	m, err := y.getMap(namespace)
+	if err != nil {
+		return nil, err
+	}
+	limits = resolve.Limits(limits)
+	ks := make([]string, 0, len(m))
+	for k := range m {
+		if k >= limits[0] && k <= limits[1] {
+			ks = append(ks, k)
+		}
+	}
+	return ks, nil
 }
 
 func (y *Yaml) Get(key string, ns ...string) ([]byte, error) {
@@ -55,7 +70,21 @@ func (y *Yaml) Get(key string, ns ...string) ([]byte, error) {
 }
 
 func (y *Yaml) GetStream(key string, ns ...string) (io.Reader, error) {
-	return nil, errors.New("not impl")
+	namespace := resolve.Namespace(ns)
+	m, err := y.getMap(namespace)
+	if err != nil {
+		return nil, err
+	}
+	v, ok := m[key]
+	if !ok {
+		return nil, ErrNotFound
+	}
+	s, ok := v.(string)
+	if !ok {
+		return nil, ErrNotFound
+	}
+	b, err := base64.StdEncoding.DecodeString(s)
+	return bytes.NewReader(b), err
 }
 
 func (y *Yaml) Set(key string, value []byte, ns ...string) error {
@@ -67,30 +96,98 @@ func (y *Yaml) Set(key string, value []byte, ns ...string) error {
 }
 
 func (y *Yaml) Del(key string, ns ...string) error {
-	return errors.New("not impl")
+	return y.SetStream(key, nil, ns...)
 }
 
 func (y *Yaml) SetStream(key string, r io.Reader, ns ...string) error {
-	return errors.New("not impl")
+	namespace := resolve.Namespace(ns)
+	var v interface{} = nil
+	if r != nil {
+		b, err := ioutil.ReadAll(r)
+		if err != nil {
+			return err
+		}
+		v = base64.StdEncoding.EncodeToString(b)
+	}
+	m, err := y.getMap()
+	if err != nil {
+		return err
+	}
+	if err := setInMap(m, []string{namespace}, key, v); err != nil {
+		return err
+	}
+	return y.setMap(m)
 }
 
 func (y *Yaml) Close() error {
 	return nil
 }
 
-func (y *Yaml) getMap() (map[string]interface{}, error) {
+func (y *Yaml) getMap(keys ...string) (map[string]interface{}, error) {
 	b, err := y.get()
 	if err != nil {
 		return nil, err
 	}
-	var m map[string]interface{}
-	err = yaml.Unmarshal(b, &m)
+	var mBad map[interface{}]interface{}
+	if err := yaml.Unmarshal(b, &mBad); err != nil {
+		return nil, err
+	}
+	m, err := mbadToM(mBad)
+	if err != nil {
+		return nil, err
+	}
+	if m == nil {
+		m = map[string]interface{}{}
+	}
+	for _, k := range keys {
+		subv, ok := m[k]
+		if !ok {
+			subv = map[string]interface{}{}
+			m[k] = subv
+		}
+		subm, ok := subv.(map[string]interface{})
+		if !ok {
+			return nil, ErrNotFound
+		}
+		m = subm
+	}
 	return m, err
 }
 
+func (y *Yaml) setMap(m map[string]interface{}) error {
+	b, err := yaml.Marshal(m)
+	if err != nil {
+		return err
+	}
+	return y.set(b)
+}
+
+func setInMap(m map[string]interface{}, keys []string, key string, v interface{}) error {
+	if len(keys) == 0 {
+		m[key] = v
+		if v == nil {
+			delete(m, key)
+		}
+		return nil
+	}
+	subv, ok := m[keys[0]]
+	if !ok {
+		subv = map[string]interface{}{}
+	}
+	subm, ok := subv.(map[string]interface{})
+	if !ok {
+		return errors.New("clobber")
+	}
+	if err := setInMap(subm, keys[1:], key, v); err != nil {
+		return err
+	}
+	m[keys[0]] = subm
+	return nil
+}
+
 func (y *Yaml) get() ([]byte, error) {
 	b, err := ioutil.ReadFile(y.path)
-	if err == os.ErrNotExist {
+	if os.IsNotExist(err) {
 		return []byte{}, nil
 	}
 	return b, err
@@ -127,3 +224,22 @@ func _keysDFS(m map[string]interface{}) ([][]string, bool, error) {
 	}
 	return keys, hasNonMaps, nil
 }
+
+func mbadToM(mBad map[interface{}]interface{}) (map[string]interface{}, error) {
+	m := map[string]interface{}{}
+	for k, v := range mBad {
+		s, ok := k.(string)
+		if !ok {
+			s = fmt.Sprint(k)
+		}
+		m[s] = v
+		if m2, ok := v.(map[interface{}]interface{}); ok {
+			v2, err := mbadToM(m2)
+			if err != nil {
+				return nil, err
+			}
+			m[s] = v2
+		}
+	}
+	return m, nil
+}
diff --git a/yaml_test.go b/yaml_test.go
index 3236a61..cac79d1 100644
--- a/yaml_test.go
+++ b/yaml_test.go
@@ -43,6 +43,17 @@ func TestKeysDFS(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
+			for j := range c.want {
+				found := false
+				for i := range got {
+					if fmt.Sprint(got[i]) == fmt.Sprint(c.want[j]) {
+						found = true
+					}
+				}
+				if !found {
+					t.Errorf("want %+v among %+v", c.want[j], got)
+				}
+			}
 			if fmt.Sprintf("%+v", got) != fmt.Sprintf("%+v", c.want) {
 				t.Fatalf("want: %+v\ngot: %+v", c.want, got)
 			}