diff --git a/usr/gri/pretty/parser.go b/usr/gri/pretty/parser.go
index 81e8af8f7f8..e74416663ae 100644
--- a/usr/gri/pretty/parser.go
+++ b/usr/gri/pretty/parser.go
@@ -190,11 +190,16 @@ func (P *Parser) ParseIdentList() *AST.Expr {
 	P.Trace("IdentList");
 
 	x := P.ParseIdent();
-	if P.tok == Scanner.COMMA {
+	for first := true; P.tok == Scanner.COMMA; {
 		pos := P.pos;
 		P.Next();
-		y := P.ParseIdentList();
-		x = P.NewExpr(pos, Scanner.COMMA, x, y);
+		y := P.ParseIdent();
+		if first {
+			x = P.NewExpr(pos, Scanner.COMMA, x, y);
+			first = false;
+		} else {
+			x.y = P.NewExpr(pos, Scanner.COMMA, x.y, y);
+		}
 	}
 
 	P.Ecart();
@@ -741,7 +746,7 @@ func (P *Parser) ParseCall(x *AST.Expr) *AST.Expr {
 }
 
 
-func (P *Parser) ParseCompositeList() *AST.Expr {
+func (P *Parser) ParseCompositeElements() *AST.Expr {
 	x := P.ParseExpression(0);
 	if P.tok == Scanner.COMMA {
 		pos := P.pos;
@@ -792,7 +797,7 @@ func (P *Parser) ParseCompositeLit(t *AST.Type) *AST.Expr {
 	x.t = t;
 	P.Expect(Scanner.LBRACE);
 	if P.tok != Scanner.RBRACE {
-		x.y = P.ParseCompositeList();
+		x.y = P.ParseCompositeElements();
 	}
 	P.Expect(Scanner.RBRACE);
 	
diff --git a/usr/gri/pretty/printer.go b/usr/gri/pretty/printer.go
index 3072b6a46e9..60f1c63bbcf 100644
--- a/usr/gri/pretty/printer.go
+++ b/usr/gri/pretty/printer.go
@@ -4,11 +4,14 @@
 
 package Printer
 
+import Strings "strings"
 import Scanner "scanner"
 import AST "ast"
 
 
 export type Printer struct {
+	pos int;  // actual output position
+
 	// formatting control
 	level int;  // true scope level
 	indent int;  // indentation level
@@ -22,11 +25,19 @@ export type Printer struct {
 }
 
 
+// Bottleneck interface - all output goes through here.
+func (P *Printer) print(s string) {
+	print(s);
+	// TODO do we need the code below?
+	// P.pos += Strings.utflen(s);
+}
+
+
 func (P *Printer) String(pos int, s string) {
 	if P.semi && P.level > 0 {  // no semicolons at level 0
 		print(";");
 	}
-	
+
 	/*
 	for pos > P.cpos {
 		// we have a comment
@@ -47,7 +58,7 @@ func (P *Printer) String(pos int, s string) {
 		}
 	}
 	*/
-	
+
 	if P.newl > 0 {
 		for i := P.newl; i > 0; i-- {
 			print("\n");
@@ -226,9 +237,10 @@ func (P *Printer) Expr1(x *AST.Expr, prec1 int) {
 
 	case Scanner.COMMA:
 		// list
-		P.Expr1(x.x, 0);
+		// (don't use binary expression printing because of different spacing)
+		P.Expr1(x.x, Scanner.LowestPrec);
 		P.String(x.pos, ", ");
-		P.Expr1(x.y, 0);
+		P.Expr1(x.y, Scanner.LowestPrec);
 
 	case Scanner.PERIOD:
 		// selector or type guard
@@ -253,36 +265,38 @@ func (P *Printer) Expr1(x *AST.Expr, prec1 int) {
 		// call
 		P.Expr1(x.x, Scanner.HighestPrec);
 		P.String(x.pos, "(");
-		P.Expr1(x.y, 0);
+		P.Expr1(x.y, Scanner.LowestPrec);
 		P.String(0, ")");
 
 	case Scanner.LBRACE:
 		// composite
 		P.Type(x.t);
 		P.String(x.pos, "{");
-		P.Expr1(x.y, 0);
+		P.Expr1(x.y, Scanner.LowestPrec);
 		P.String(0, "}");
 		
 	default:
-		// unary and binary expressions
+		// unary and binary expressions including ":" for pairs
+		prec := Scanner.UnaryPrec;
+		if x.x != nil {
+			prec = Scanner.Precedence(x.tok);
+		}
+		if prec < prec1 {
+			P.String(0, "(");
+		}
 		if x.x == nil {
 			// unary expression
 			P.Token(x.pos, x.tok);
-			P.Expr1(x.y, Scanner.UnaryPrec);
 		} else {
-			// binary expression: print ()'s if necessary
-			prec := Scanner.Precedence(x.tok);
-			if prec < prec1 {
-				P.String(0, "(");
-			}
+			// binary expression
 			P.Expr1(x.x, prec);
 			P.Blank();
 			P.Token(x.pos, x.tok);
 			P.Blank();
-			P.Expr1(x.y, prec);
-			if prec < prec1 {
-				P.String(0, ")");
-			}
+		}
+		P.Expr1(x.y, prec);
+		if prec < prec1 {
+			P.String(0, ")");
 		}
 	}
 }
diff --git a/usr/gri/pretty/test.sh b/usr/gri/pretty/test.sh
index de0003d862d..2af37703856 100755
--- a/usr/gri/pretty/test.sh
+++ b/usr/gri/pretty/test.sh
@@ -71,6 +71,17 @@ idempotent() {
 }
 
 
+valid() {
+	cleanup
+	pretty $1 > $TMP1
+	6g -o /dev/null $TMP1
+	if [ $? != 0 ]; then
+		echo "Error (validity test): test.sh $1"
+		exit 1
+	fi
+}
+
+
 runtest() {
 	#echo "Testing silent mode"
 	cleanup
@@ -79,6 +90,10 @@ runtest() {
 	#echo "Testing idempotency"
 	cleanup
 	$1 idempotent $2
+
+	#echo "Testing validity"
+	#cleanup
+	#$1 valid $2
 }