diff --git a/cmd/cmsh/main.go b/cmd/cmsh/main.go
index 817e72d..44f1921 100644
--- a/cmd/cmsh/main.go
+++ b/cmd/cmsh/main.go
@@ -24,6 +24,7 @@ func main() {
 		ucl.WithModule(builtins.Itrs()),
 		ucl.WithModule(builtins.OS()),
 		ucl.WithModule(builtins.Strs()),
+		ucl.WithModule(builtins.Lists()),
 		ucl.WithModule(builtins.Time()),
 	)
 	ctx := context.Background()
diff --git a/cmd/playwasm/jsiter.go b/cmd/playwasm/jsiter.go
index c1201ab..72723cd 100644
--- a/cmd/playwasm/jsiter.go
+++ b/cmd/playwasm/jsiter.go
@@ -27,6 +27,7 @@ func initJS(ctx context.Context) {
 		ucl.WithModule(builtins.Strs()),
 		ucl.WithModule(builtins.Time()),
 		ucl.WithModule(builtins.Itrs()),
+		ucl.WithModule(builtins.Lists()),
 		ucl.WithOut(ucl.LineHandler(func(line string) {
 			invokeUCLCallback("onOutLine", line)
 		})),
diff --git a/ucl/builtins.go b/ucl/builtins.go
index 56c8f56..96db044 100644
--- a/ucl/builtins.go
+++ b/ucl/builtins.go
@@ -451,12 +451,58 @@ func callBuiltin(ctx context.Context, args invocationArgs) (Object, error) {
 		return nil, err
 	}
 
-	inv, ok := args.args[0].(invokable)
-	if !ok {
-		return nil, errors.New("expected invokable")
+	var inv invokable
+	switch t := args.args[0].(type) {
+	case invokable:
+		inv = t
+	case StringObject:
+		inv = args.ec.lookupInvokable(t.String())
+		if inv == nil {
+			return nil, errors.New("no such invokable: " + t.String())
+		}
+	default:
+		return nil, errors.New("expected string or invokable")
 	}
 
-	return inv.invoke(ctx, args.shift(1))
+	var calledArgs []Object
+
+	args = args.shift(1)
+	if len(args.args) > 0 {
+		argList, ok := args.args[0].(Listable)
+		if !ok {
+			return nil, errors.New("expected listable arg")
+		}
+		calledArgs = make([]Object, argList.Len())
+		for i := 0; i < argList.Len(); i++ {
+			calledArgs[i] = argList.Index(i)
+		}
+		args.shift(1)
+	}
+
+	invArgs := args.fork(calledArgs)
+
+	args = args.shift(1)
+	if len(args.args) > 0 {
+		kwArgs, ok := args.args[0].(Hashable)
+		if !ok {
+			return nil, errors.New("expected hashable arg")
+		}
+		kwArgs.Each(func(k string, v Object) error {
+			if invArgs.kwargs == nil {
+				invArgs.kwargs = make(map[string]*ListObject)
+			}
+			if invArgs.kwargs[k] == nil {
+				invArgs.kwargs[k] = &ListObject{}
+			}
+
+			kwArg := *(invArgs.kwargs[k])
+			kwArg = append(kwArg, v)
+			invArgs.kwargs[k] = &kwArg
+			return nil
+		})
+	}
+
+	return inv.invoke(ctx, invArgs)
 }
 
 func lenBuiltin(ctx context.Context, args invocationArgs) (Object, error) {
@@ -495,6 +541,8 @@ func indexLookup(ctx context.Context, obj, elem Object) (Object, error) {
 		}
 		if int(intIdx) >= 0 && int(intIdx) < v.Len() {
 			return v.Index(int(intIdx)), nil
+		} else if int(intIdx) < 0 && int(intIdx) >= -v.Len() {
+			return v.Index(v.Len() + int(intIdx)), nil
 		}
 		return nil, nil
 	case Hashable:
diff --git a/ucl/builtins/lists.go b/ucl/builtins/lists.go
new file mode 100644
index 0000000..f81f3e2
--- /dev/null
+++ b/ucl/builtins/lists.go
@@ -0,0 +1,60 @@
+package builtins
+
+import (
+	"context"
+	"errors"
+	"ucl.lmika.dev/ucl"
+)
+
+func Lists() ucl.Module {
+	return ucl.Module{
+		Name: "lists",
+		Builtins: map[string]ucl.BuiltinHandler{
+			"first": listFirst,
+		},
+	}
+}
+
+func listFirst(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var (
+		what  ucl.Object
+		count int
+	)
+
+	if err := args.Bind(&what, &count); err != nil {
+		return nil, err
+	}
+
+	if count == 0 {
+		return ucl.NewListObject(), nil
+	}
+
+	newList := ucl.NewListObject()
+
+	switch t := what.(type) {
+	case ucl.Listable:
+		if count < 0 {
+			count = t.Len() + count
+		}
+
+		for i := 0; i < min(count, t.Len()); i++ {
+			newList.Append(t.Index(i))
+		}
+	case ucl.Iterable:
+		if count < 0 {
+			return nil, errors.New("negative counts not supported on iters")
+		}
+
+		for i := 0; t.HasNext() && i < count; i++ {
+			v, err := t.Next(ctx)
+			if err != nil {
+				return nil, err
+			}
+			newList.Append(v)
+		}
+	default:
+		return nil, errors.New("expected listable")
+	}
+
+	return newList, nil
+}
diff --git a/ucl/builtins/lists_test.go b/ucl/builtins/lists_test.go
new file mode 100644
index 0000000..ca86731
--- /dev/null
+++ b/ucl/builtins/lists_test.go
@@ -0,0 +1,59 @@
+package builtins_test
+
+import (
+	"context"
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"ucl.lmika.dev/ucl"
+	"ucl.lmika.dev/ucl/builtins"
+)
+
+func TestLists_First(t *testing.T) {
+	tests := []struct {
+		desc    string
+		eval    string
+		want    any
+		wantErr bool
+	}{
+		{desc: "firsts 1", eval: `lists:first [1 2 3 4 5] 0`, want: []any{}},
+		{desc: "firsts 2", eval: `lists:first [1 2 3 4 5] 3`, want: []any{1, 2, 3}},
+		{desc: "firsts 3", eval: `lists:first [1 2 3] 5`, want: []any{1, 2, 3}},
+		{desc: "firsts 4", eval: `lists:first [1 2 3] 1`, want: []any{1}},
+		{desc: "firsts 5", eval: `lists:first [1 2 3 4 5] -1`, want: []any{1, 2, 3, 4}},
+		{desc: "firsts 6", eval: `lists:first [1 2 3 4 5] -3`, want: []any{1, 2}},
+		{desc: "firsts 7", eval: `lists:first [1 2 3 4 5] -8`, want: []any{}},
+		{desc: "firsts 8", eval: `lists:first (itrs:from [1 2 3 4 5]) 3`, want: []any{1, 2, 3}},
+		{desc: "firsts 9", eval: `lists:first (itrs:from [1 2 3]) 5`, want: []any{1, 2, 3}},
+
+		{desc: "err 1", eval: `lists:first (itrs:from [1 2 3]) -3`, wantErr: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			inst := ucl.New(
+				ucl.WithModule(builtins.Itrs()),
+				ucl.WithModule(builtins.Lists()),
+			)
+			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)
+			}
+		})
+	}
+}
+
+func uclListOf(args ...any) *ucl.ListObject {
+	newList := ucl.NewListObject()
+	for _, arg := range args {
+		switch t := arg.(type) {
+		case int:
+			newList.Append(ucl.IntObject(t))
+		default:
+			panic("unhandled type")
+		}
+	}
+	return newList
+}
diff --git a/ucl/builtins/strs.go b/ucl/builtins/strs.go
index a10893d..fb6a3d3 100644
--- a/ucl/builtins/strs.go
+++ b/ucl/builtins/strs.go
@@ -2,6 +2,7 @@ package builtins
 
 import (
 	"context"
+	"errors"
 	"strings"
 	"ucl.lmika.dev/ucl"
 )
@@ -10,9 +11,12 @@ func Strs() ucl.Module {
 	return ucl.Module{
 		Name: "strs",
 		Builtins: map[string]ucl.BuiltinHandler{
-			"to-upper": toUpper,
-			"to-lower": toLower,
-			"trim":     trim,
+			"to-upper":   toUpper,
+			"to-lower":   toLower,
+			"trim":       trim,
+			"split":      split,
+			"join":       join,
+			"has-prefix": hasPrefix,
 		},
 	}
 }
@@ -43,3 +47,86 @@ func trim(ctx context.Context, args ucl.CallArgs) (any, error) {
 
 	return strings.TrimSpace(s), nil
 }
+
+func hasPrefix(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var s, prefix string
+	if err := args.Bind(&s, &prefix); err != nil {
+		return nil, err
+	}
+
+	return strings.HasPrefix(s, prefix), nil
+}
+
+func split(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var s string
+	if err := args.Bind(&s); err != nil {
+		return nil, err
+	}
+
+	sep := ""
+	if args.NArgs() > 0 {
+		if err := args.Bind(&sep); err != nil {
+			return nil, err
+		}
+	}
+
+	n := -1
+	if args.HasSwitch("max") {
+		if err := args.BindSwitch("max", &n); err != nil {
+			return nil, err
+		}
+	}
+
+	return StringSlice(strings.SplitN(s, sep, n)), nil
+}
+
+func join(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var (
+		what ucl.Object
+		tok  string
+	)
+
+	if err := args.Bind(&what); err != nil {
+		return nil, err
+	}
+
+	if args.NArgs() > 0 {
+		if err := args.Bind(&tok); err != nil {
+			return nil, err
+		}
+	}
+
+	switch t := what.(type) {
+	case ucl.Listable:
+		var sb strings.Builder
+		for i := 0; i < t.Len(); i++ {
+			if i > 0 {
+				sb.WriteString(tok)
+			}
+			sb.WriteString(t.Index(i).String())
+		}
+		return sb.String(), nil
+	case ucl.Iterable:
+		first := true
+
+		var sb strings.Builder
+		for t.HasNext() {
+			v, err := t.Next(ctx)
+			if err != nil {
+				return nil, err
+			}
+			if !first {
+				sb.WriteString(tok)
+			} else {
+				first = false
+			}
+			sb.WriteString(v.String())
+		}
+
+		return sb.String(), nil
+	}
+
+	return nil, errors.New("expected listable or iterable as arg 1")
+}
+
+type StringSlice []string
diff --git a/ucl/builtins/strs_test.go b/ucl/builtins/strs_test.go
index c6ef90a..6af7082 100644
--- a/ucl/builtins/strs_test.go
+++ b/ucl/builtins/strs_test.go
@@ -100,3 +100,104 @@ func TestStrs_Trim(t *testing.T) {
 		})
 	}
 }
+
+func TestStrs_HasPrefix(t *testing.T) {
+	tests := []struct {
+		desc    string
+		eval    string
+		want    any
+		wantErr bool
+	}{
+		{desc: "has prefix 1", eval: `strs:has-prefix "hello, world" "hello"`, want: true},
+		{desc: "has prefix 2", eval: `strs:has-prefix "goodbye, world" "hello"`, want: false},
+		{desc: "has prefix 3", eval: `strs:has-prefix "" "world"`, want: false},
+		{desc: "has prefix 4", eval: `strs:has-prefix "hello" ""`, want: true},
+
+		{desc: "err 1", eval: `strs:has-prefix`, wantErr: true},
+		{desc: "err 1", eval: `strs:has-prefix "asd"`, wantErr: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			inst := ucl.New(
+				ucl.WithModule(builtins.Strs()),
+			)
+			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)
+			}
+		})
+	}
+}
+
+func TestStrs_Split(t *testing.T) {
+	tests := []struct {
+		desc    string
+		eval    string
+		want    any
+		wantErr bool
+	}{
+		{desc: "split 1", eval: `strs:split "1,2,3" ","`, want: builtins.StringSlice{"1", "2", "3"}},
+		{desc: "split 2", eval: `strs:split "1,2,3" ";"`, want: builtins.StringSlice{"1,2,3"}},
+		{desc: "split 3", eval: `strs:split "" ";"`, want: builtins.StringSlice{""}},
+		{desc: "split 4", eval: `strs:split " " ";"`, want: builtins.StringSlice{" "}},
+
+		{desc: "split by char 1", eval: `strs:split "123"`, want: builtins.StringSlice{"1", "2", "3"}},
+
+		{desc: "split max 1", eval: `strs:split "1,2,3" "," -max 2`, want: builtins.StringSlice{"1", "2,3"}},
+		{desc: "split max 2", eval: `strs:split "1,2,3" "," -max 5`, want: builtins.StringSlice{"1", "2", "3"}},
+
+		{desc: "split by char max 1", eval: `strs:split "12345" -max 3`, want: builtins.StringSlice{"1", "2", "345"}},
+
+		{desc: "err 1", eval: `strs:split "1,2,3" -max []`, wantErr: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			inst := ucl.New(
+				ucl.WithModule(builtins.Strs()),
+			)
+			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)
+			}
+		})
+	}
+}
+
+func TestStrs_Join(t *testing.T) {
+	tests := []struct {
+		desc    string
+		eval    string
+		want    any
+		wantErr bool
+	}{
+		{desc: "join 1", eval: `strs:join [1 2 3] ","`, want: "1,2,3"},
+		{desc: "join 2", eval: `strs:join [a b c] " "`, want: "a b c"},
+		{desc: "join 3", eval: `strs:join [a b c] ""`, want: "abc"},
+		{desc: "join 4", eval: `strs:join [a b c]`, want: "abc"},
+		{desc: "join 5", eval: `strs:join (itrs:from [a b c]) ","`, want: "a,b,c"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			inst := ucl.New(
+				ucl.WithModule(builtins.Itrs()),
+				ucl.WithModule(builtins.Strs()),
+			)
+			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/builtins/time.go b/ucl/builtins/time.go
index bfbf495..fcc804d 100644
--- a/ucl/builtins/time.go
+++ b/ucl/builtins/time.go
@@ -11,6 +11,7 @@ func Time() ucl.Module {
 		Name: "time",
 		Builtins: map[string]ucl.BuiltinHandler{
 			"from-unix": timeFromUnix,
+			"sleep":     timeSleep,
 		},
 	}
 }
@@ -24,3 +25,18 @@ func timeFromUnix(ctx context.Context, args ucl.CallArgs) (any, error) {
 
 	return time.Unix(int64(ux), 0).UTC(), nil
 }
+
+func timeSleep(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var secs int
+
+	if err := args.Bind(&secs); err != nil {
+		return nil, err
+	}
+
+	select {
+	case <-time.After(time.Duration(secs) * time.Second):
+		return nil, nil
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
diff --git a/ucl/builtins/time_test.go b/ucl/builtins/time_test.go
index 2e14c59..4c95b5a 100644
--- a/ucl/builtins/time_test.go
+++ b/ucl/builtins/time_test.go
@@ -35,3 +35,21 @@ func TestTime_FromUnix(t *testing.T) {
 		})
 	}
 }
+
+func TestTime_Sleep(t *testing.T) {
+	t.Run("should terminate on cancelled context", func(t *testing.T) {
+		st := time.Now()
+
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+
+		inst := ucl.New(
+			ucl.WithModule(builtins.Time()),
+		)
+
+		_, err := inst.Eval(ctx, `time:sleep 1`)
+		assert.Error(t, err)
+		assert.Equal(t, "context canceled", err.Error())
+		assert.True(t, time.Now().Sub(st) < time.Second)
+	})
+}
diff --git a/ucl/inst_test.go b/ucl/inst_test.go
index 47e8eff..429b35b 100644
--- a/ucl/inst_test.go
+++ b/ucl/inst_test.go
@@ -80,20 +80,25 @@ func TestInst_Eval(t *testing.T) {
 		{desc: "map 6", expr: `set x [a:"A" b:"B" c:"C"] ; firstarg ["one":$x.c "two":$x.b "three":$x.a]`, want: map[string]any{"one": "C", "two": "B", "three": "A"}},
 
 		// Dots
-		{desc: "dot 1", expr: `set x [1 2 3] ; $x.(0)`, want: 1},
-		{desc: "dot 2", expr: `set x [1 2 3] ; $x.(1)`, want: 2},
-		{desc: "dot 3", expr: `set x [1 2 3] ; $x.(2)`, want: 3},
-		{desc: "dot 4", expr: `set x [1 2 3] ; $x.(3)`, want: nil},
-		{desc: "dot 5", expr: `set x [1 2 3] ; $x.(add 1 1)`, want: 3},
-		{desc: "dot 6", expr: `set x [alpha:"hello" bravo:"world"] ; $x.alpha`, want: "hello"},
-		{desc: "dot 7", expr: `set x [alpha:"hello" bravo:"world"] ; $x.bravo`, want: "world"},
-		{desc: "dot 8", expr: `set x [alpha:"hello" bravo:"world"] ; $x.charlie`, want: nil},
-		{desc: "dot 9", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("alpha")`, want: "hello"},
-		{desc: "dot 10", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("bravo")`, want: "world"},
-		{desc: "dot 11", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("charlie")`, want: nil},
-		{desc: "dot 12", expr: `set x [MORE:"stuff"] ; $x.("more" | toUpper)`, want: "stuff"},
-		{desc: "dot 13", expr: `set x [MORE:"stuff"] ; $x.(toUpper ("more"))`, want: "stuff"},
-		{desc: "dot 14", expr: `set x [MORE:"stuff"] ; x.y`, want: nil},
+		{desc: "dot expr 1", expr: `set x [1 2 3] ; $x.(0)`, want: 1},
+		{desc: "dot expr 2", expr: `set x [1 2 3] ; $x.(1)`, want: 2},
+		{desc: "dot expr 3", expr: `set x [1 2 3] ; $x.(2)`, want: 3},
+		{desc: "dot expr 4", expr: `set x [1 2 3] ; $x.(3)`, want: nil},
+		{desc: "dot expr 5", expr: `set x [1 2 3] ; $x.(add 1 1)`, want: 3},
+		{desc: "dot expr 6", expr: `set x [1 2 3] ; $x.(-1)`, want: 3},
+		{desc: "dot expr 7", expr: `set x [1 2 3] ; $x.(-2)`, want: 2},
+		{desc: "dot expr 8", expr: `set x [1 2 3] ; $x.(-3)`, want: 1},
+		{desc: "dot expr 9", expr: `set x [1 2 3] ; $x.(-4)`, want: nil},
+
+		{desc: "dot idents 1", expr: `set x [alpha:"hello" bravo:"world"] ; $x.alpha`, want: "hello"},
+		{desc: "dot idents 2", expr: `set x [alpha:"hello" bravo:"world"] ; $x.bravo`, want: "world"},
+		{desc: "dot idents 3", expr: `set x [alpha:"hello" bravo:"world"] ; $x.charlie`, want: nil},
+		{desc: "dot idents 4", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("alpha")`, want: "hello"},
+		{desc: "dot idents 5", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("bravo")`, want: "world"},
+		{desc: "dot idents 6", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("charlie")`, want: nil},
+		{desc: "dot idents 7", expr: `set x [MORE:"stuff"] ; $x.("more" | toUpper)`, want: "stuff"},
+		{desc: "dot idents 8", expr: `set x [MORE:"stuff"] ; $x.(toUpper ("more"))`, want: "stuff"},
+		{desc: "dot idents 9", expr: `set x [MORE:"stuff"] ; x.y`, want: nil},
 
 		{desc: "parse comments 1", expr: parseComments1, wantErr: ucl.ErrNotConvertable},
 		{desc: "parse comments 2", expr: parseComments2, wantErr: ucl.ErrNotConvertable},
diff --git a/ucl/objs.go b/ucl/objs.go
index b4b0c2a..e2bfda9 100644
--- a/ucl/objs.go
+++ b/ucl/objs.go
@@ -437,7 +437,7 @@ func (ia invocationArgs) fork(args []Object) invocationArgs {
 		inst:   ia.inst,
 		ec:     ia.ec,
 		args:   args,
-		kwargs: make(map[string]*ListObject),
+		kwargs: nil,
 	}
 }
 
diff --git a/ucl/testbuiltins_test.go b/ucl/testbuiltins_test.go
index 8cb8cfe..e138a1c 100644
--- a/ucl/testbuiltins_test.go
+++ b/ucl/testbuiltins_test.go
@@ -493,7 +493,7 @@ func TestBuiltins_Procs(t *testing.T) {
 			set goodbye (makeGreeter "Goodbye cruel")
 			$goodbye "world"
 
-			call (makeGreeter "Quick") "call me"
+			call (makeGreeter "Quick") ["call me"]
 
 			`, want: "Hello, world\nGoodbye cruel, world\nQuick, call me\n(nil)\n"},
 		{desc: "modifying closed over variables", expr: `
@@ -505,8 +505,8 @@ func TestBuiltins_Procs(t *testing.T) {
 			}
 		
 			set er (makeSetter)
-			echo (call $er "xxx")
-			echo (call $er "yyy")
+			echo (call $er ["xxx"])
+			echo (call $er ["yyy"])
 			`, want: "Xxxx\nXxxxyyy\n(nil)\n"},
 	}