diff --git a/cmdlang/ast.go b/cmdlang/ast.go
index 0a29001..dc10311 100644
--- a/cmdlang/ast.go
+++ b/cmdlang/ast.go
@@ -11,16 +11,35 @@ type astLiteral struct {
 	Str *string `parser:"@String"`
 }
 
+type astHashKey struct {
+	Literal *astLiteral  `parser:"@@"`
+	Ident   *string      `parser:"| @Ident"`
+	Var     *string      `parser:"| DOLLAR @Ident"`
+	Sub     *astPipeline `parser:"| LP @@ RP"`
+}
+
+type astElementPair struct {
+	Left  astCmdArg  `parser:"@@"`
+	Right *astCmdArg `parser:"( COLON @@ )? NL?"`
+}
+
+type astListOrHash struct {
+	EmptyList bool              `parser:"@(LS RS)"`
+	EmptyHash bool              `parser:"| @(LS COLON RS)"`
+	Elements  []*astElementPair `parser:"| LS NL? @@+ @@* RS"`
+}
+
 type astBlock struct {
 	Statements []*astStatements `parser:"LC NL? @@ NL? RC"`
 }
 
 type astCmdArg struct {
-	Literal *astLiteral  `parser:"@@"`
-	Ident   *string      `parser:"| @Ident"`
-	Var     *string      `parser:"| DOLLAR @Ident"`
-	Sub     *astPipeline `parser:"| LP @@ RP"`
-	Block   *astBlock    `parser:"| @@"`
+	Literal    *astLiteral    `parser:"@@"`
+	Ident      *string        `parser:"| @Ident"`
+	Var        *string        `parser:"| DOLLAR @Ident"`
+	Sub        *astPipeline   `parser:"| LP @@ RP"`
+	ListOrHash *astListOrHash `parser:"| @@"`
+	Block      *astBlock      `parser:"| @@"`
 }
 
 type astCmd struct {
@@ -47,8 +66,11 @@ var scanner = lexer.MustStateful(lexer.Rules{
 		{"Whitespace", `[ \t]+`, nil},
 		{"String", `"(\\"|[^"])*"`, nil},
 		{"DOLLAR", `\$`, nil},
+		{"COLON", `\:`, nil},
 		{"LP", `\(`, nil},
 		{"RP", `\)`, nil},
+		{"LS", `\[`, nil},
+		{"RS", `\]`, nil},
 		{"LC", `\{`, nil},
 		{"RC", `\}`, nil},
 		{"NL", `[;\n][; \n\t]*`, nil},
diff --git a/cmdlang/eval.go b/cmdlang/eval.go
index 77cd445..38eb13b 100644
--- a/cmdlang/eval.go
+++ b/cmdlang/eval.go
@@ -130,12 +130,57 @@ func (e evaluator) evalArg(ctx context.Context, ec *evalCtx, n astCmdArg) (objec
 		return nil, nil
 	case n.Sub != nil:
 		return e.evalSub(ctx, ec, n.Sub)
+	case n.ListOrHash != nil:
+		return e.evalListOrHash(ctx, ec, n.ListOrHash)
 	case n.Block != nil:
 		return blockObject{block: n.Block}, nil
 	}
 	return nil, errors.New("unhandled arg type")
 }
 
+func (e evaluator) evalListOrHash(ctx context.Context, ec *evalCtx, loh *astListOrHash) (object, error) {
+	if loh.EmptyList {
+		return listObject{}, nil
+	} else if loh.EmptyHash {
+		return hashObject{}, nil
+	}
+
+	if firstIsHash := loh.Elements[0].Right != nil; firstIsHash {
+		h := hashObject{}
+		for _, el := range loh.Elements {
+			if el.Right == nil {
+				return nil, errors.New("miss-match of lists and hash")
+			}
+
+			n, err := e.evalArg(ctx, ec, el.Left)
+			if err != nil {
+				return nil, err
+			}
+
+			v, err := e.evalArg(ctx, ec, *el.Right)
+			if err != nil {
+				return nil, err
+			}
+
+			h[n.String()] = v
+		}
+		return h, nil
+	}
+
+	l := listObject{}
+	for _, el := range loh.Elements {
+		if el.Right != nil {
+			return nil, errors.New("miss-match of lists and hash")
+		}
+		v, err := e.evalArg(ctx, ec, el.Left)
+		if err != nil {
+			return nil, err
+		}
+		l = append(l, v)
+	}
+	return l, nil
+}
+
 func (e evaluator) evalLiteral(ctx context.Context, ec *evalCtx, n *astLiteral) (object, error) {
 	switch {
 	case n.Str != nil:
diff --git a/cmdlang/inst_test.go b/cmdlang/inst_test.go
index beec7a8..bc5619b 100644
--- a/cmdlang/inst_test.go
+++ b/cmdlang/inst_test.go
@@ -13,7 +13,7 @@ func TestInst_Eval(t *testing.T) {
 	tests := []struct {
 		desc string
 		expr string
-		want string
+		want any
 	}{
 		{desc: "simple string", expr: `firstarg "hello"`, want: "hello"},
 		{desc: "simple ident", expr: `firstarg a-test`, want: "a-test"},
@@ -39,6 +39,23 @@ func TestInst_Eval(t *testing.T) {
 		{desc: "multi 1", expr: `firstarg "hello" ; firstarg "world"`, want: "world"},
 		{desc: "multi 2", expr: `pipe "hello" | toUpper ; firstarg "world"`, want: "world"}, // TODO: assert for leaks
 		{desc: "multi 3", expr: `set new "this is new" ; firstarg $new`, want: "this is new"},
+
+		// Lists
+		{desc: "list 1", expr: `firstarg ["1" "2" "3"]`, want: []any{"1", "2", "3"}},
+		{desc: "list 2", expr: `set one "one" ; firstarg [$one (pipe "two" | toUpper) "three"]`, want: []any{"one", "TWO", "three"}},
+		{desc: "list 3", expr: `firstarg []`, want: []any{}},
+
+		// Maps
+		{desc: "map 1", expr: `firstarg [one:"1" two:"2" three:"3"]`, want: map[string]any{"one": "1", "two": "2", "three": "3"}},
+		{desc: "map 2", expr: `firstarg ["one":"1" "two":"2" "three":"3"]`, want: map[string]any{"one": "1", "two": "2", "three": "3"}},
+		{desc: "map 3", expr: `
+			set one "one" ; set n1 "1"
+			firstarg [
+				$one:$n1
+				(firstarg "two" | toUpper):(firstarg "2" | toUpper)
+				three:"3"
+			]`, want: map[string]any{"one": "1", "TWO": "2", "three": "3"}},
+		{desc: "map 4", expr: `firstarg [:]`, want: map[string]any{}},
 	}
 
 	for _, tt := range tests {
diff --git a/cmdlang/objs.go b/cmdlang/objs.go
index 49cb1f5..9bba180 100644
--- a/cmdlang/objs.go
+++ b/cmdlang/objs.go
@@ -12,6 +12,26 @@ type object interface {
 	Truthy() bool
 }
 
+type listObject []object
+
+func (s listObject) String() string {
+	return fmt.Sprintf("%v", []object(s))
+}
+
+func (s listObject) Truthy() bool {
+	return len(s) > 0
+}
+
+type hashObject map[string]object
+
+func (s hashObject) String() string {
+	return fmt.Sprintf("%v", map[string]object(s))
+}
+
+func (s hashObject) Truthy() bool {
+	return len(s) > 0
+}
+
 type strObject string
 
 func (s strObject) String() string {
@@ -28,6 +48,26 @@ func toGoValue(obj object) (interface{}, bool) {
 		return nil, true
 	case strObject:
 		return string(v), true
+	case listObject:
+		xs := make([]interface{}, 0, len(v))
+		for _, va := range v {
+			x, ok := toGoValue(va)
+			if !ok {
+				continue
+			}
+			xs = append(xs, x)
+		}
+		return xs, true
+	case hashObject:
+		xs := make(map[string]interface{})
+		for k, va := range v {
+			x, ok := toGoValue(va)
+			if !ok {
+				continue
+			}
+			xs[k] = x
+		}
+		return xs, true
 	case proxyObject:
 		return v.p, true
 	}