diff --git a/client/go/internal/vespa/slime/array.go b/client/go/internal/vespa/slime/array.go
new file mode 100644
index 000000000000..371c2340bc0e
--- /dev/null
+++ b/client/go/internal/vespa/slime/array.go
@@ -0,0 +1,29 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+type arrayValue struct {
+	emptyValue
+	value []Value
+}
+
+func Array() *arrayValue       { return &arrayValue{} }
+func (*arrayValue) Type() Type { return ARRAY }
+
+func (arr *arrayValue) NumEntries() int { return len(arr.value) }
+func (arr *arrayValue) Entry(index int) Value {
+	if index < len(arr.value) {
+		return arr.value[index]
+	}
+	return Invalid
+}
+func (arr *arrayValue) EachEntry(f func(index int, value Value)) {
+	for i, x := range arr.value {
+		f(i, x)
+	}
+}
+
+func (arr *arrayValue) Add(value Value) Value {
+	arr.value = append(arr.value, value)
+	return value
+}
diff --git a/client/go/internal/vespa/slime/array_test.go b/client/go/internal/vespa/slime/array_test.go
new file mode 100644
index 000000000000..c8006badac19
--- /dev/null
+++ b/client/go/internal/vespa/slime/array_test.go
@@ -0,0 +1,42 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestArray(t *testing.T) {
+	arr := Array()
+	actual := []Value{
+		arr.Add(Empty),
+		arr.Add(Bool(true)),
+		arr.Add(Long(5)),
+		arr.Add(Double(5.5)),
+		arr.Add(String("foo")),
+		arr.Add(Data([]byte{1, 2, 3}))}
+
+	expect := []expectLeaf{
+		expectLeaf{mytype: EMPTY},
+		expectLeaf{mytype: BOOL, boolVal: true},
+		expectLeaf{mytype: LONG, longVal: 5, doubleVal: 5},
+		expectLeaf{mytype: DOUBLE, longVal: 5, doubleVal: 5.5},
+		expectLeaf{mytype: STRING, stringVal: "foo"},
+		expectLeaf{mytype: DATA, dataVal: []byte{1, 2, 3}}}
+
+	var expectIndex int
+	var collect []Value
+	arr.EachEntry(func(idx int, val Value) {
+		assert.Equal(t, idx, expectIndex)
+		collect = append(collect, val)
+		expectIndex++
+	})
+
+	assert.Equal(t, arr.NumEntries(), len(expect))
+	for i, e := range expect {
+		checkLeaf(t, actual[i], e)
+		checkLeaf(t, collect[i], e)
+		checkLeaf(t, arr.Entry(i), e)
+	}
+}
diff --git a/client/go/internal/vespa/slime/leaf.go b/client/go/internal/vespa/slime/leaf.go
new file mode 100644
index 000000000000..d2e6c8399f90
--- /dev/null
+++ b/client/go/internal/vespa/slime/leaf.go
@@ -0,0 +1,50 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+type boolValue struct {
+	emptyValue
+	value bool
+}
+
+func Bool(v bool) Value           { return &boolValue{value: v} }
+func (*boolValue) Type() Type     { return BOOL }
+func (v *boolValue) AsBool() bool { return v.value }
+
+type longValue struct {
+	emptyValue
+	value int64
+}
+
+func Long(v int64) Value               { return &longValue{value: v} }
+func (*longValue) Type() Type          { return LONG }
+func (v *longValue) AsLong() int64     { return v.value }
+func (v *longValue) AsDouble() float64 { return float64(v.value) }
+
+type doubleValue struct {
+	emptyValue
+	value float64
+}
+
+func Double(v float64) Value             { return &doubleValue{value: v} }
+func (*doubleValue) Type() Type          { return DOUBLE }
+func (v *doubleValue) AsLong() int64     { return int64(v.value) }
+func (v *doubleValue) AsDouble() float64 { return v.value }
+
+type stringValue struct {
+	emptyValue
+	value string
+}
+
+func String(v string) Value             { return &stringValue{value: v} }
+func (*stringValue) Type() Type         { return STRING }
+func (v *stringValue) AsString() string { return v.value }
+
+type dataValue struct {
+	emptyValue
+	value []byte
+}
+
+func Data(v []byte) Value           { return &dataValue{value: v} }
+func (*dataValue) Type() Type       { return DATA }
+func (v *dataValue) AsData() []byte { return v.value }
diff --git a/client/go/internal/vespa/slime/leaf_test.go b/client/go/internal/vespa/slime/leaf_test.go
new file mode 100644
index 000000000000..501af06c6620
--- /dev/null
+++ b/client/go/internal/vespa/slime/leaf_test.go
@@ -0,0 +1,65 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+type expectLeaf struct {
+	invalid   bool
+	mytype    Type
+	boolVal   bool
+	longVal   int64
+	doubleVal float64
+	stringVal string
+	dataVal   []byte
+}
+
+func checkLeaf(t *testing.T, value Value, expect expectLeaf) {
+	if expect.dataVal == nil {
+		expect.dataVal = emptyBytes
+	}
+	assert.Equal(t, value.Valid(), !expect.invalid)
+	assert.Equal(t, value.Type(), expect.mytype)
+	assert.Equal(t, value.AsBool(), expect.boolVal)
+	assert.Equal(t, value.AsLong(), expect.longVal)
+	assert.Equal(t, value.AsDouble(), expect.doubleVal)
+	assert.Equal(t, value.AsString(), expect.stringVal)
+	assert.Equal(t, value.AsData(), expect.dataVal)
+}
+
+func TestEmpty(t *testing.T) {
+	checkLeaf(t, Empty, expectLeaf{})
+	checkLeaf(t, Invalid, expectLeaf{invalid: true})
+}
+
+func TestBool(t *testing.T) {
+	checkLeaf(t, Bool(false), expectLeaf{mytype: BOOL})
+	checkLeaf(t, Bool(true), expectLeaf{mytype: BOOL, boolVal: true})
+}
+
+func TestLong(t *testing.T) {
+	checkLeaf(t, Long(0), expectLeaf{mytype: LONG})
+	checkLeaf(t, Long(5), expectLeaf{mytype: LONG, longVal: 5, doubleVal: 5})
+	checkLeaf(t, Long(7), expectLeaf{mytype: LONG, longVal: 7, doubleVal: 7})
+}
+
+func TestDouble(t *testing.T) {
+	checkLeaf(t, Double(0.0), expectLeaf{mytype: DOUBLE})
+	checkLeaf(t, Double(5.0), expectLeaf{mytype: DOUBLE, longVal: 5, doubleVal: 5.0})
+	checkLeaf(t, Double(7.5), expectLeaf{mytype: DOUBLE, longVal: 7, doubleVal: 7.5})
+}
+
+func TestString(t *testing.T) {
+	checkLeaf(t, String(""), expectLeaf{mytype: STRING})
+	checkLeaf(t, String("foo"), expectLeaf{mytype: STRING, stringVal: "foo"})
+	checkLeaf(t, String("bar"), expectLeaf{mytype: STRING, stringVal: "bar"})
+}
+
+func TestData(t *testing.T) {
+	checkLeaf(t, Data(emptyBytes), expectLeaf{mytype: DATA})
+	checkLeaf(t, Data([]byte{1, 2, 3}), expectLeaf{mytype: DATA, dataVal: []byte{1, 2, 3}})
+	checkLeaf(t, Data([]byte{5, 6}), expectLeaf{mytype: DATA, dataVal: []byte{5, 6}})
+}
diff --git a/client/go/internal/vespa/slime/object.go b/client/go/internal/vespa/slime/object.go
new file mode 100644
index 000000000000..c1c8610a01fe
--- /dev/null
+++ b/client/go/internal/vespa/slime/object.go
@@ -0,0 +1,34 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+type objectValue struct {
+	emptyValue
+	value map[string]Value
+}
+
+func Object() Value             { return &objectValue{value: make(map[string]Value)} }
+func (*objectValue) Type() Type { return OBJECT }
+
+func (obj *objectValue) NumFields() int { return len(obj.value) }
+func (obj *objectValue) Field(name string) Value {
+	value, found := obj.value[name]
+	if found {
+		return value
+	}
+	return Invalid
+}
+func (obj *objectValue) EachField(f func(name string, value Value)) {
+	for n, x := range obj.value {
+		f(n, x)
+	}
+}
+
+func (obj *objectValue) Set(name string, value Value) Value {
+	_, found := obj.value[name]
+	if found {
+		return Invalid
+	}
+	obj.value[name] = value
+	return value
+}
diff --git a/client/go/internal/vespa/slime/object_test.go b/client/go/internal/vespa/slime/object_test.go
new file mode 100644
index 000000000000..8beea3b00d8e
--- /dev/null
+++ b/client/go/internal/vespa/slime/object_test.go
@@ -0,0 +1,40 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestObject(t *testing.T) {
+	obj := Object()
+	actual := map[string]Value{
+		"a": obj.Set("a", Empty),
+		"b": obj.Set("b", Bool(true)),
+		"c": obj.Set("c", Long(5)),
+		"d": obj.Set("d", Double(5.5)),
+		"e": obj.Set("e", String("foo")),
+		"f": obj.Set("f", Data([]byte{1, 2, 3}))}
+
+	expect := map[string]expectLeaf{
+		"a": expectLeaf{mytype: EMPTY},
+		"b": expectLeaf{mytype: BOOL, boolVal: true},
+		"c": expectLeaf{mytype: LONG, longVal: 5, doubleVal: 5},
+		"d": expectLeaf{mytype: DOUBLE, longVal: 5, doubleVal: 5.5},
+		"e": expectLeaf{mytype: STRING, stringVal: "foo"},
+		"f": expectLeaf{mytype: DATA, dataVal: []byte{1, 2, 3}}}
+
+	collect := make(map[string]Value)
+	obj.EachField(func(name string, val Value) {
+		collect[name] = val
+	})
+
+	assert.Equal(t, obj.NumFields(), len(expect))
+	assert.Equal(t, len(collect), len(expect))
+	for n, e := range expect {
+		checkLeaf(t, actual[n], e)
+		checkLeaf(t, collect[n], e)
+		checkLeaf(t, obj.Field(n), e)
+	}
+}
diff --git a/client/go/internal/vespa/slime/type.go b/client/go/internal/vespa/slime/type.go
new file mode 100644
index 000000000000..fdead48dd85e
--- /dev/null
+++ b/client/go/internal/vespa/slime/type.go
@@ -0,0 +1,16 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+type Type byte
+
+const (
+	EMPTY Type = iota
+	BOOL
+	LONG
+	DOUBLE
+	STRING
+	DATA
+	ARRAY
+	OBJECT
+)
diff --git a/client/go/internal/vespa/slime/value.go b/client/go/internal/vespa/slime/value.go
new file mode 100644
index 000000000000..f48143f4fc82
--- /dev/null
+++ b/client/go/internal/vespa/slime/value.go
@@ -0,0 +1,45 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package slime
+
+var (
+	emptyBytes []byte = make([]byte, 0)
+	Empty      Value  = &emptyValue{}
+	Invalid    Value  = (*emptyValue)(nil)
+)
+
+type Value interface {
+	Valid() bool
+	Type() Type
+	AsBool() bool
+	AsLong() int64
+	AsDouble() float64
+	AsString() string
+	AsData() []byte
+	NumEntries() int
+	Entry(index int) Value
+	EachEntry(func(index int, value Value))
+	NumFields() int
+	Field(name string) Value
+	EachField(func(name string, value Value))
+	Add(value Value) Value
+	Set(name string, value Value) Value
+}
+
+type emptyValue struct{}
+
+func (v *emptyValue) Valid() bool                            { return (v != nil) }
+func (*emptyValue) Type() Type                               { return EMPTY }
+func (*emptyValue) AsBool() bool                             { return false }
+func (*emptyValue) AsLong() int64                            { return 0 }
+func (*emptyValue) AsDouble() float64                        { return 0 }
+func (*emptyValue) AsString() string                         { return "" }
+func (*emptyValue) AsData() []byte                           { return emptyBytes }
+func (*emptyValue) NumEntries() int                          { return 0 }
+func (*emptyValue) Entry(index int) Value                    { return Invalid }
+func (*emptyValue) EachEntry(func(index int, value Value))   {}
+func (*emptyValue) NumFields() int                           { return 0 }
+func (*emptyValue) Field(name string) Value                  { return Invalid }
+func (*emptyValue) EachField(func(name string, value Value)) {}
+func (*emptyValue) Add(value Value) Value                    { return Invalid }
+func (*emptyValue) Set(name string, value Value) Value       { return Invalid }