diff --git a/ucl/ast.go b/ucl/ast.go
index 97374cc..8b118ad 100644
--- a/ucl/ast.go
+++ b/ucl/ast.go
@@ -13,13 +13,24 @@ type astStringStringSpan struct {
 	Chars *string `parser:"@SingleChar"`
 }
 
+type astLongIdentDotSuffix struct {
+	KeyName  *string      `parser:"@LIIdent"`
+	Pipeline *astPipeline `parser:"| LILp @@ RP"`
+}
+
+type astLongIdent struct {
+	Pos       lexer.Position
+	VarName   string                  `parser:"@LIIdent"`
+	DotSuffix []astLongIdentDotSuffix `parser:"( LIDot @@ )*"`
+}
+
 type astDoubleStringSpan struct {
 	Pos          lexer.Position
-	Chars        *string      `parser:"@Char"`
-	Escaped      *string      `parser:"| @Escaped"`
-	IdentRef     *string      `parser:"| @IdentRef"`
-	LongIdentRef *string      `parser:"| @LongIdentRef"`
-	SubExpr      *astPipeline `parser:"| StartSubExpr @@ RP"`
+	Chars        *string       `parser:"@Char"`
+	Escaped      *string       `parser:"| @Escaped"`
+	IdentRef     *string       `parser:"| @IdentRef"`
+	LongIdentRef *astLongIdent `parser:"| LongIdentRef @@ LIEnd"`
+	SubExpr      *astPipeline  `parser:"| StartSubExpr @@ RP"`
 }
 
 type astDoubleString struct {
@@ -134,10 +145,16 @@ var scanner = lexer.MustStateful(lexer.Rules{
 		{"Escaped", `\\.`, nil},
 		{"StringEnd", `"`, lexer.Pop()},
 		{"IdentRef", `\$[-]*[a-zA-Z_][\w-]*`, nil},
-		{"LongIdentRef", `\$[{][^}]*[}]`, nil},
+		{"LongIdentRef", `\$[{]`, lexer.Push("LongIdent")},
 		{"StartSubExpr", `\$[(]`, lexer.Push("Root")},
 		{"Char", `[^$"\\]+`, nil},
 	},
+	"LongIdent": {
+		{"LIIdent", `[-]*[a-zA-Z_][\w-]*`, nil},
+		{"LIDot", `[.]`, nil},
+		{"LILp", `\(`, lexer.Push("Root")},
+		{"LIEnd", `\}`, lexer.Pop()},
+	},
 	"SingleString": {
 		{"SingleStringEnd", `'`, lexer.Pop()},
 		{"SingleChar", `[^']+`, nil},
diff --git a/ucl/builtins/time.go b/ucl/builtins/time.go
new file mode 100644
index 0000000..bfbf495
--- /dev/null
+++ b/ucl/builtins/time.go
@@ -0,0 +1,26 @@
+package builtins
+
+import (
+	"context"
+	"time"
+	"ucl.lmika.dev/ucl"
+)
+
+func Time() ucl.Module {
+	return ucl.Module{
+		Name: "time",
+		Builtins: map[string]ucl.BuiltinHandler{
+			"from-unix": timeFromUnix,
+		},
+	}
+}
+
+func timeFromUnix(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var ux int
+
+	if err := args.Bind(&ux); err != nil {
+		return nil, err
+	}
+
+	return time.Unix(int64(ux), 0).UTC(), nil
+}
diff --git a/ucl/builtins/time_test.go b/ucl/builtins/time_test.go
new file mode 100644
index 0000000..2e14c59
--- /dev/null
+++ b/ucl/builtins/time_test.go
@@ -0,0 +1,37 @@
+package builtins_test
+
+import (
+	"context"
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"time"
+	"ucl.lmika.dev/ucl"
+	"ucl.lmika.dev/ucl/builtins"
+)
+
+func TestTime_FromUnix(t *testing.T) {
+	tests := []struct {
+		desc    string
+		eval    string
+		want    any
+		wantErr bool
+	}{
+		{desc: "from unix 1", eval: `time:from-unix 0`, want: time.Unix(0, 0).UTC()},
+		{desc: "from unix 2", eval: `time:from-unix 0 | cat`, want: "1970-01-01T00:00:00Z"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			inst := ucl.New(
+				ucl.WithModule(builtins.Time()),
+			)
+			res, err := inst.Eval(context.Background(), tt.eval)
+			if tt.wantErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tt.want, res)
+			}
+		})
+	}
+}
diff --git a/ucl/eval.go b/ucl/eval.go
index 6edea36..ad33e63 100644
--- a/ucl/eval.go
+++ b/ucl/eval.go
@@ -3,6 +3,7 @@ package ucl
 import (
 	"context"
 	"errors"
+	"fmt"
 	"strings"
 )
 
@@ -299,10 +300,11 @@ func (e evaluator) interpolateDoubleQuotedString(ctx context.Context, ec *evalCt
 				sb.WriteString(v.String())
 			}
 		case n.LongIdentRef != nil:
-			identVal := (*n.LongIdentRef)[2 : len(*n.LongIdentRef)-1]
-			if v, ok := ec.getVar(identVal); ok && v != nil {
-				sb.WriteString(v.String())
+			v, err := e.interpolateLongIdent(ctx, ec, n.LongIdentRef)
+			if err != nil {
+				return nil, err
 			}
+			sb.WriteString(v)
 		case n.SubExpr != nil:
 			res, err := e.evalPipeline(ctx, ec, n.SubExpr)
 			if err != nil {
@@ -316,6 +318,38 @@ func (e evaluator) interpolateDoubleQuotedString(ctx context.Context, ec *evalCt
 	return StringObject(sb.String()), nil
 }
 
+func (e evaluator) interpolateLongIdent(ctx context.Context, ec *evalCtx, n *astLongIdent) (_ string, err error) {
+	res, ok := ec.getVar(n.VarName)
+	if !ok {
+		return "", nil
+	}
+
+	for _, dot := range n.DotSuffix {
+		if res == nil {
+			return "", errorWithPos{fmt.Errorf("attempt to get field from nil value '%v'", n.VarName), n.Pos}
+		}
+
+		var idx Object
+		if dot.KeyName != nil {
+			idx = StringObject(*dot.KeyName)
+		} else {
+			idx, err = e.evalPipeline(ctx, ec, dot.Pipeline)
+			if err != nil {
+				return "", err
+			}
+		}
+
+		res, err = indexLookup(ctx, res, idx)
+		if err != nil {
+			return "", err
+		}
+	}
+	if res == nil {
+		return "", nil
+	}
+	return res.String(), nil
+}
+
 func (e evaluator) evalSub(ctx context.Context, ec *evalCtx, n *astPipeline) (Object, error) {
 	pipelineRes, err := e.evalPipeline(ctx, ec, n)
 	if err != nil {
diff --git a/ucl/inst_test.go b/ucl/inst_test.go
index 5d1ac79..ca20469 100644
--- a/ucl/inst_test.go
+++ b/ucl/inst_test.go
@@ -25,11 +25,15 @@ func TestInst_Eval(t *testing.T) {
 		{desc: "interpolate string 1", expr: `set what "world" ; firstarg "hello $what"`, want: "hello world"},
 		{desc: "interpolate string 2", expr: `set what "world" ; set when "now" ; firstarg "$when, hello $what"`, want: "now, hello world"},
 		{desc: "interpolate string 3", expr: `set what "world" ; set when "now" ; firstarg "${when}, hello ${what}"`, want: "now, hello world"},
-		{desc: "interpolate string 4", expr: `set "crazy var" "unknown" ; firstarg "hello ${crazy var}"`, want: "hello unknown"},
-		{desc: "interpolate string 5", expr: `set what "world" ; firstarg "hello $($what)"`, want: "hello world"},
-		{desc: "interpolate string 6", expr: `firstarg "hello $([1 2 3] | len)"`, want: "hello 3"},
-		{desc: "interpolate string 7", expr: `firstarg "hello $(add (add 1 2) 3)"`, want: "hello 6"},
-		{desc: "interpolate string 8", expr: `firstarg ("$(add 2 (add 1 1)) + $([1 2 3].(1) | cat ("$("")")) = $(("$(add 2 (4))"))")`, want: "4 + 2 = 6"},
+		{desc: "interpolate string 4", expr: `set crazy [far: "unknown"] ; firstarg "hello ${crazy.far}"`, want: "hello unknown"},
+		{desc: "interpolate string 5", expr: `set oldWords ["hither" "thither" "yonder"] ; firstarg "hello ${oldWords.(1)}"`, want: "hello thither"},
+		{desc: "interpolate string 6", expr: `set oldWords ["hither" "thither" "yonder"] ; firstarg "hello ${oldWords.(add 1 1)}"`, want: "hello yonder"},
+		{desc: "interpolate string 7", expr: `set oldWords ["hither" "thither" "yonder"] ; firstarg "hello ${oldWords.(add 2 | sub (sub 2 1) | sub 1)}"`, want: "hello hither"},
+		{desc: "interpolate string 8", expr: `set words ["old": ["hither" "thither" "yonder"] "new": ["near" "far"]] ; firstarg "hello ${words.old.(2)}"`, want: "hello yonder"},
+		{desc: "interpolate string 9", expr: `set what "world" ; firstarg "hello $($what)"`, want: "hello world"},
+		{desc: "interpolate string 10", expr: `firstarg "hello $([1 2 3] | len)"`, want: "hello 3"},
+		{desc: "interpolate string 11", expr: `firstarg "hello $(add (add 1 2) 3)"`, want: "hello 6"},
+		{desc: "interpolate string 12", expr: `firstarg ("$(add 2 (add 1 1)) + $([1 2 3].(1) | cat ("$("")")) = $(("$(add 2 (4))"))")`, want: "4 + 2 = 6"},
 
 		// Sub-expressions
 		{desc: "sub expression 1", expr: `firstarg (sjoin "hello")`, want: "hello"},
diff --git a/ucl/objs.go b/ucl/objs.go
index 8e18095..71575c4 100644
--- a/ucl/objs.go
+++ b/ucl/objs.go
@@ -7,34 +7,35 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/lmika/gopkgs/fp/slices"
 )
 
-type object interface {
+type Object interface {
 	String() string
 	Truthy() bool
 }
 
-type listable interface {
+type Listable interface {
 	Len() int
-	Index(i int) object
+	Index(i int) Object
 }
 
 type hashable interface {
 	Len() int
-	Value(k string) object
-	Each(func(k string, v object) error) error
+	Value(k string) Object
+	Each(func(k string, v Object) error) error
 }
 
-type listObject []object
+type listObject []Object
 
-func (lo *listObject) Append(o object) {
+func (lo *listObject) Append(o Object) {
 	*lo = append(*lo, o)
 }
 
 func (s listObject) String() string {
-	return fmt.Sprintf("%v", []object(s))
+	return fmt.Sprintf("%v", []Object(s))
 }
 
 func (s listObject) Truthy() bool {
@@ -45,11 +46,11 @@ func (s listObject) Len() int {
 	return len(s)
 }
 
-func (s listObject) Index(i int) object {
+func (s listObject) Index(i int) Object {
 	return s[i]
 }
 
-type hashObject map[string]object
+type hashObject map[string]Object
 
 func (s hashObject) String() string {
 	if len(s) == 0 {
@@ -78,11 +79,11 @@ func (s hashObject) Len() int {
 	return len(s)
 }
 
-func (s hashObject) Value(k string) object {
+func (s hashObject) Value(k string) Object {
 	return s[k]
 }
 
-func (s hashObject) Each(fn func(k string, v object) error) error {
+func (s hashObject) Each(fn func(k string, v Object) error) error {
 	for k, v := range s {
 		if err := fn(k, v); err != nil {
 			return err
@@ -91,13 +92,13 @@ func (s hashObject) Each(fn func(k string, v object) error) error {
 	return nil
 }
 
-type strObject string
+type StringObject string
 
-func (s strObject) String() string {
+func (s StringObject) String() string {
 	return string(s)
 }
 
-func (s strObject) Truthy() bool {
+func (s StringObject) Truthy() bool {
 	return string(s) != ""
 }
 
@@ -124,16 +125,28 @@ func (b boolObject) Truthy() bool {
 	return bool(b)
 }
 
-func toGoValue(obj object) (interface{}, bool) {
+type timeObject time.Time
+
+func (t timeObject) String() string {
+	return time.Time(t).Format(time.RFC3339)
+}
+
+func (t timeObject) Truthy() bool {
+	return !time.Time(t).IsZero()
+}
+
+func toGoValue(obj Object) (interface{}, bool) {
 	switch v := obj.(type) {
 	case nil:
 		return nil, true
-	case strObject:
+	case StringObject:
 		return string(v), true
 	case intObject:
 		return int(v), true
 	case boolObject:
 		return bool(v), true
+	case timeObject:
+		return time.Time(v), true
 	case listObject:
 		xs := make([]interface{}, 0, len(v))
 		for _, va := range v {
@@ -157,42 +170,62 @@ func toGoValue(obj object) (interface{}, bool) {
 	case proxyObject:
 		return v.p, true
 	case listableProxyObject:
-		return v.v.Interface(), true
+		return v.orig.Interface(), true
 	case structProxyObject:
-		return v.v.Interface(), true
+		return v.orig.Interface(), true
 	}
 
 	return nil, false
 }
 
-func fromGoValue(v any) (object, error) {
+func fromGoValue(v any) (Object, error) {
 	switch t := v.(type) {
+	case Object:
+		return t, nil
 	case nil:
 		return nil, nil
 	case string:
-		return strObject(t), nil
+		return StringObject(t), nil
 	case int:
 		return intObject(t), nil
 	case bool:
 		return boolObject(t), nil
+	case time.Time:
+		return timeObject(t), nil
+	}
+
+	return fromGoReflectValue(reflect.ValueOf(v))
+}
+
+func fromGoReflectValue(resVal reflect.Value) (Object, error) {
+	if !resVal.IsValid() {
+		return nil, nil
 	}
 
-	resVal := reflect.ValueOf(v)
 	switch resVal.Kind() {
 	case reflect.Slice:
-		return listableProxyObject{resVal}, nil
+		return listableProxyObject{v: resVal, orig: resVal}, nil
 	case reflect.Struct:
-		return newStructProxyObject(resVal), nil
+		return newStructProxyObject(resVal, resVal), nil
+	case reflect.Pointer:
+		switch resVal.Elem().Kind() {
+		case reflect.Slice:
+			return listableProxyObject{v: resVal.Elem(), orig: resVal}, nil
+		case reflect.Struct:
+			return newStructProxyObject(resVal.Elem(), resVal), nil
+		}
+
+		return fromGoReflectValue(resVal.Elem())
 	}
 
-	return proxyObject{v}, nil
+	return proxyObject{resVal.Interface()}, nil
 }
 
 type macroArgs struct {
 	eval     evaluator
 	ec       *evalCtx
 	hasPipe  bool
-	pipeArg  object
+	pipeArg  Object
 	ast      *astCmd
 	argShift int
 }
@@ -239,7 +272,7 @@ func (ma *macroArgs) shiftIdent(ctx context.Context) (string, bool) {
 	return "", false
 }
 
-func (ma macroArgs) evalArg(ctx context.Context, n int) (object, error) {
+func (ma macroArgs) evalArg(ctx context.Context, n int) (Object, error) {
 	if n >= len(ma.ast.Args[ma.argShift:]) {
 		return nil, errors.New("not enough arguments") // FIX
 	}
@@ -247,7 +280,7 @@ func (ma macroArgs) evalArg(ctx context.Context, n int) (object, error) {
 	return ma.eval.evalDot(ctx, ma.ec, ma.ast.Args[ma.argShift+n])
 }
 
-func (ma macroArgs) evalBlock(ctx context.Context, n int, args []object, pushScope bool) (object, error) {
+func (ma macroArgs) evalBlock(ctx context.Context, n int, args []Object, pushScope bool) (Object, error) {
 	obj, err := ma.evalArg(ctx, n)
 	if err != nil {
 		return nil, err
@@ -266,7 +299,7 @@ func (ma macroArgs) evalBlock(ctx context.Context, n int, args []object, pushSco
 		}
 
 		return ma.eval.evalBlock(ctx, ec, v.block)
-	case strObject:
+	case StringObject:
 		iv := ma.ec.lookupInvokable(string(v))
 		if iv == nil {
 			return nil, errors.New("'" + string(v) + "' is not invokable")
@@ -297,7 +330,7 @@ type invocationArgs struct {
 	eval   evaluator
 	inst   *Inst
 	ec     *evalCtx
-	args   []object
+	args   []Object
 	kwargs map[string]*listObject
 }
 
@@ -340,7 +373,7 @@ func (ia invocationArgs) invokableArg(i int) (invokable, error) {
 	switch v := ia.args[i].(type) {
 	case invokable:
 		return v, nil
-	case strObject:
+	case StringObject:
 		iv := ia.ec.lookupInvokable(string(v))
 		if iv == nil {
 			return nil, errors.New("'" + string(v) + "' is not invokable")
@@ -350,7 +383,7 @@ func (ia invocationArgs) invokableArg(i int) (invokable, error) {
 	return nil, errors.New("expected an invokable arg")
 }
 
-func (ia invocationArgs) fork(args []object) invocationArgs {
+func (ia invocationArgs) fork(args []Object) invocationArgs {
 	return invocationArgs{
 		eval:   ia.eval,
 		inst:   ia.inst,
@@ -373,27 +406,28 @@ func (ia invocationArgs) shift(i int) invocationArgs {
 	}
 }
 
-// invokable is an object that can be executed as a command
+// invokable is an Object that can be executed as a command
 type invokable interface {
-	invoke(ctx context.Context, args invocationArgs) (object, error)
+	invoke(ctx context.Context, args invocationArgs) (Object, error)
 }
 
 type macroable interface {
-	invokeMacro(ctx context.Context, args macroArgs) (object, error)
+	invokeMacro(ctx context.Context, args macroArgs) (Object, error)
 }
 
 type pipeInvokable interface {
 	invokable
 }
 
-type invokableFunc func(ctx context.Context, args invocationArgs) (object, error)
+type invokableFunc func(ctx context.Context, args invocationArgs) (Object, error)
 
-func (i invokableFunc) invoke(ctx context.Context, args invocationArgs) (object, error) {
+func (i invokableFunc) invoke(ctx context.Context, args invocationArgs) (Object, error) {
 	return i(ctx, args)
 }
 
 type blockObject struct {
-	block *astBlock
+	block    *astBlock
+	closedEC *evalCtx
 }
 
 func (bo blockObject) String() string {
@@ -404,8 +438,8 @@ func (bo blockObject) Truthy() bool {
 	return len(bo.block.Statements) > 0
 }
 
-func (bo blockObject) invoke(ctx context.Context, args invocationArgs) (object, error) {
-	ec := args.ec.fork()
+func (bo blockObject) invoke(ctx context.Context, args invocationArgs) (Object, error) {
+	ec := bo.closedEC.fork()
 	for i, n := range bo.block.Names {
 		if i < len(args.args) {
 			ec.setOrDefineVar(n, args.args[i])
@@ -415,13 +449,13 @@ func (bo blockObject) invoke(ctx context.Context, args invocationArgs) (object,
 	return args.eval.evalBlock(ctx, ec, bo.block)
 }
 
-type macroFunc func(ctx context.Context, args macroArgs) (object, error)
+type macroFunc func(ctx context.Context, args macroArgs) (Object, error)
 
-func (i macroFunc) invokeMacro(ctx context.Context, args macroArgs) (object, error) {
+func (i macroFunc) invokeMacro(ctx context.Context, args macroArgs) (Object, error) {
 	return i(ctx, args)
 }
 
-func isTruthy(obj object) bool {
+func isTruthy(obj Object) bool {
 	if obj == nil {
 		return false
 	}
@@ -441,7 +475,8 @@ func (p proxyObject) Truthy() bool {
 }
 
 type listableProxyObject struct {
-	v reflect.Value
+	v    reflect.Value
+	orig reflect.Value
 }
 
 func (p listableProxyObject) String() string {
@@ -456,7 +491,7 @@ func (p listableProxyObject) Len() int {
 	return p.v.Len()
 }
 
-func (p listableProxyObject) Index(i int) object {
+func (p listableProxyObject) Index(i int) Object {
 	e, err := fromGoValue(p.v.Index(i).Interface())
 	if err != nil {
 		return nil
@@ -465,14 +500,16 @@ func (p listableProxyObject) Index(i int) object {
 }
 
 type structProxyObject struct {
-	v  reflect.Value
-	vf []reflect.StructField
+	v    reflect.Value
+	orig reflect.Value
+	vf   []reflect.StructField
 }
 
-func newStructProxyObject(v reflect.Value) structProxyObject {
+func newStructProxyObject(v reflect.Value, orig reflect.Value) structProxyObject {
 	return structProxyObject{
-		v:  v,
-		vf: slices.Filter(reflect.VisibleFields(v.Type()), func(t reflect.StructField) bool { return t.IsExported() }),
+		v:    v,
+		orig: orig,
+		vf:   slices.Filter(reflect.VisibleFields(v.Type()), func(t reflect.StructField) bool { return t.IsExported() }),
 	}
 }
 
@@ -488,7 +525,7 @@ func (s structProxyObject) Len() int {
 	return len(s.vf)
 }
 
-func (s structProxyObject) Value(k string) object {
+func (s structProxyObject) Value(k string) Object {
 	f := s.v.FieldByName(k)
 	if !f.IsValid() {
 		return nil
@@ -508,7 +545,7 @@ func (s structProxyObject) Value(k string) object {
 	return e
 }
 
-func (s structProxyObject) Each(fn func(k string, v object) error) error {
+func (s structProxyObject) Each(fn func(k string, v Object) error) error {
 	for _, f := range s.vf {
 		v, err := fromGoValue(s.v.FieldByName(f.Name).Interface())
 		if err != nil {
@@ -522,9 +559,25 @@ func (s structProxyObject) Each(fn func(k string, v object) error) error {
 	return nil
 }
 
+type OpaqueObject struct {
+	v any
+}
+
+func Opaque(v any) OpaqueObject {
+	return OpaqueObject{v: v}
+}
+
+func (p OpaqueObject) String() string {
+	return fmt.Sprintf("opaque{%T}", p.v)
+}
+
+func (p OpaqueObject) Truthy() bool {
+	return p.v != nil
+}
+
 type errBreak struct {
 	isCont bool
-	ret    object
+	ret    Object
 }
 
 func (e errBreak) Error() string {
@@ -535,7 +588,7 @@ func (e errBreak) Error() string {
 }
 
 type errReturn struct {
-	ret object
+	ret Object
 }
 
 func (e errReturn) Error() string {