diff --git a/usr/gri/pretty/ast.go b/usr/gri/pretty/ast.go
index ec5af4b8c5..cf8f5b125e 100644
--- a/usr/gri/pretty/ast.go
+++ b/usr/gri/pretty/ast.go
@@ -7,6 +7,7 @@ package ast
 import (
 	"vector";
 	"token";
+	"scanner";
 )
 
 
@@ -27,15 +28,6 @@ func assert(pred bool) {
 }
 
 
-// ----------------------------------------------------------------------------
-// All nodes have a source position and a token.
-
-type Node struct {
-	Pos int;  // source position (< 0 => unknown position)
-	Tok int;  // identifying token
-}
-
-
 // ----------------------------------------------------------------------------
 // Expressions
 
@@ -51,27 +43,27 @@ type (
 	Signature struct;
 
 	Expr interface {
-		Pos() int;
+		Loc() scanner.Location;
 		Visit(v ExprVisitor);
 	};
 	
 	BadExpr struct {
-		Pos_ int;
+		Loc_ scanner.Location;
 	};
 
 	Ident struct {
-		Pos_ int;
+		Loc_ scanner.Location;
 		Str string;
 	};
 
 	BinaryExpr struct {
-		Pos_ int;
+		Loc_ scanner.Location;
 		Tok int;
 		X, Y Expr;
 	};
 
 	UnaryExpr struct {
-		Pos_ int;
+		Loc_ scanner.Location;
 		Tok int;
 		X Expr;
 	};
@@ -82,56 +74,56 @@ type (
 	};
 
 	BasicLit struct {
-		Pos_ int;
+		Loc_ scanner.Location;
 		Tok int;
 		Val []byte;
 	};
 
 	FunctionLit struct {
-		Pos_ int;  // position of "func"
+		Loc_ scanner.Location;  // location of "func"
 		Typ *Signature;
 		Body *Block;
 	};
 	
 	Group struct {
-		Pos_ int;  // position of "("
+		Loc_ scanner.Location;  // location of "("
 		X Expr;
 	};
 
 	Selector struct {
-		Pos_ int;  // position of "."
+		Loc_ scanner.Location;  // location of "."
 		X Expr;
 		Sel *Ident;
 	};
 
 	TypeGuard struct {
-		Pos_ int;  // position of "."
+		Loc_ scanner.Location;  // location of "."
 		X Expr;
 		Typ Expr;
 	};
 
 	Index struct {
-		Pos_ int;  // position of "["
+		Loc_ scanner.Location;  // location of "["
 		X, I Expr;
 	};
 	
 	Call struct {
-		Pos_ int;  // position of "(" or "{"
+		Loc_ scanner.Location;  // location of "(" or "{"
 		Tok int;
 		F, Args Expr
 	};
 
 	// Type literals are treated like expressions.
 	Ellipsis struct {  // neither a type nor an expression
-		Pos_ int;
+		Loc_ scanner.Location;
 	};
 	
 	TypeType struct {  // for type switches
-		Pos_ int;  // position of "type"
+		Loc_ scanner.Location;  // location of "type"
 	};
 
 	ArrayType struct {
-		Pos_ int;  // position of "["
+		Loc_ scanner.Location;  // location of "["
 		Len Expr;
 		Elt Expr;
 	};
@@ -143,13 +135,13 @@ type (
 	};
 
 	StructType struct {
-		Pos_ int;  // position of "struct"
+		Loc_ scanner.Location;  // location of "struct"
 		Fields []*Field;
-		End int;  // position of "}", End == 0 if forward declaration
+		End scanner.Location;  // location of "}"
 	};
 	
 	PointerType struct {
-		Pos_ int;  // position of "*"
+		Loc_ scanner.Location;  // location of "*"
 		Base Expr;
 	};
 	
@@ -159,28 +151,28 @@ type (
 	};
 
 	FunctionType struct {
-		Pos_ int;  // position of "func"
+		Loc_ scanner.Location;  // location of "func"
 		Sig *Signature;
 	};
 
 	InterfaceType struct {
-		Pos_ int;  // position of "interface"
+		Loc_ scanner.Location;  // location of "interface"
 		Methods []*Field;
-		End int;  // position of "}", End == 0 if forward declaration
+		End scanner.Location;  // location of "}", End == 0 if forward declaration
 	};
 
 	SliceType struct {
-		Pos_ int;  // position of "["
+		Loc_ scanner.Location;  // location of "["
 	};
 	
 	MapType struct {
-		Pos_ int;  // position of "map"
+		Loc_ scanner.Location;  // location of "map"
 		Key Expr;
 		Val Expr;
 	};
 	
 	ChannelType struct {
-		Pos_ int;  // position of "chan" or "<-"
+		Loc_ scanner.Location;  // location of "chan" or "<-"
 		Mode int;
 		Val Expr;
 	};
@@ -215,29 +207,29 @@ type ExprVisitor interface {
 
 
 // TODO replace these with an embedded field
-func (x *BadExpr) Pos() int { return x.Pos_; }
-func (x *Ident) Pos() int { return x.Pos_; }
-func (x *BinaryExpr) Pos() int { return x.Pos_; }
-func (x *UnaryExpr) Pos() int { return x.Pos_; }
-func (x *ConcatExpr) Pos() int { return x.X.Pos(); }
-func (x *BasicLit) Pos() int { return x.Pos_; }
-func (x *FunctionLit) Pos() int { return x.Pos_; }
-func (x *Group) Pos() int { return x.Pos_; }
-func (x *Selector) Pos() int { return x.Pos_; }
-func (x *TypeGuard) Pos() int { return x.Pos_; }
-func (x *Index) Pos() int { return x.Pos_; }
-func (x *Call) Pos() int { return x.Pos_; }
+func (x *BadExpr) Loc() scanner.Location { return x.Loc_; }
+func (x *Ident) Loc() scanner.Location { return x.Loc_; }
+func (x *BinaryExpr) Loc() scanner.Location { return x.Loc_; }
+func (x *UnaryExpr) Loc() scanner.Location { return x.Loc_; }
+func (x *ConcatExpr) Loc() scanner.Location { return x.X.Loc(); }
+func (x *BasicLit) Loc() scanner.Location { return x.Loc_; }
+func (x *FunctionLit) Loc() scanner.Location { return x.Loc_; }
+func (x *Group) Loc() scanner.Location { return x.Loc_; }
+func (x *Selector) Loc() scanner.Location { return x.Loc_; }
+func (x *TypeGuard) Loc() scanner.Location { return x.Loc_; }
+func (x *Index) Loc() scanner.Location { return x.Loc_; }
+func (x *Call) Loc() scanner.Location { return x.Loc_; }
 
-func (x *Ellipsis) Pos() int { return x.Pos_; }
-func (x *TypeType) Pos() int { return x.Pos_; }
-func (x *ArrayType) Pos() int { return x.Pos_; }
-func (x *StructType) Pos() int { return x.Pos_; }
-func (x *PointerType) Pos() int { return x.Pos_; }
-func (x *FunctionType) Pos() int { return x.Pos_; }
-func (x *InterfaceType) Pos() int { return x.Pos_; }
-func (x *SliceType) Pos() int { return x.Pos_; }
-func (x *MapType) Pos() int { return x.Pos_; }
-func (x *ChannelType) Pos() int { return x.Pos_; }
+func (x *Ellipsis) Loc() scanner.Location { return x.Loc_; }
+func (x *TypeType) Loc() scanner.Location { return x.Loc_; }
+func (x *ArrayType) Loc() scanner.Location { return x.Loc_; }
+func (x *StructType) Loc() scanner.Location { return x.Loc_; }
+func (x *PointerType) Loc() scanner.Location { return x.Loc_; }
+func (x *FunctionType) Loc() scanner.Location { return x.Loc_; }
+func (x *InterfaceType) Loc() scanner.Location { return x.Loc_; }
+func (x *SliceType) Loc() scanner.Location { return x.Loc_; }
+func (x *MapType) Loc() scanner.Location { return x.Loc_; }
+func (x *ChannelType) Loc() scanner.Location { return x.Loc_; }
 
 
 func (x *BadExpr) Visit(v ExprVisitor) { v.DoBadExpr(x); }
@@ -305,17 +297,17 @@ func ExprAt(x Expr, i int) Expr {
 //   ":" StatementList
 
 type Block struct {
-	Node;
+	Loc scanner.Location;
+	Tok int;
 	List *vector.Vector;
-	End int;  // position of closing "}" if present
+	End scanner.Location;  // location of closing "}" if present
 }
 
 
-func NewBlock(pos, tok int) *Block {
+func NewBlock(loc scanner.Location, tok int) *Block {
 	assert(tok == token.LBRACE || tok == token.COLON);
-	b := new(Block);
-	b.Pos, b.Tok, b.List = pos, tok, vector.New(0);
-	return b;
+	var end scanner.Location;
+	return &Block{loc, tok, vector.New(0), end};
 }
 
 
@@ -330,11 +322,11 @@ type (
 	};
 	
 	BadStat struct {
-		Pos int;
+		Loc scanner.Location;
 	};
 
 	LabelDecl struct {
-		Pos int;  // position of ":"
+		Loc scanner.Location;  // location of ":"
 		Label *Ident;
 	};
 
@@ -343,7 +335,7 @@ type (
 	};
 
 	ExpressionStat struct {
-		Pos int;  // position of Tok
+		Loc scanner.Location;  // location of Tok
 		Tok int;  // INC, DEC, RETURN, GO, DEFER
 		Expr Expr;
 	};
@@ -353,7 +345,7 @@ type (
 	};
 
 	IfStat struct {
-		Pos int;  // position of "if"
+		Loc scanner.Location;  // location of "if"
 		Init Stat;
 		Cond Expr;
 		Body *Block;
@@ -361,7 +353,7 @@ type (
 	};
 	
 	ForStat struct {
-		Pos int;  // position of "for"
+		Loc scanner.Location;  // location of "for"
 		Init Stat;
 		Cond Expr;
 		Post Stat;
@@ -369,31 +361,31 @@ type (
 	};
 
 	CaseClause struct {
-		Pos int;  // position for "case" or "default"
+		Loc scanner.Location;  // position for "case" or "default"
 		Expr Expr;  // nil means default case
 		Body *Block;
 	};
 
 	SwitchStat struct {
-		Pos int;  // position of "switch"
+		Loc scanner.Location;  // location of "switch"
 		Init Stat;
 		Tag Expr;
 		Body *Block;
 	};
 	
 	SelectStat struct {
-		Pos int;  // position of "select"
+		Loc scanner.Location;  // location of "select"
 		Body *Block;
 	};
 	
 	ControlFlowStat struct {
-		Pos int;  // position of Tok
+		Loc scanner.Location;  // location of Tok
 		Tok int;  // BREAK, CONTINUE, GOTO, FALLTHROUGH
 		Label *Ident;  // if any, or nil
 	};
 	
 	EmptyStat struct {
-		Pos int;  // position of ";"
+		Loc scanner.Location;  // location of ";"
 	};
 )
 
@@ -439,37 +431,37 @@ type (
 	};
 	
 	BadDecl struct {
-		Pos int;
+		Loc scanner.Location;
 	};
 
 	ImportDecl struct {
-		Pos int;  // if > 0: position of "import"
+		Loc scanner.Location;  // if > 0: position of "import"
 		Ident *Ident;
 		Path Expr;
 	};
 	
 	ConstDecl struct {
-		Pos int;  // if > 0: position of "const"
+		Loc scanner.Location;  // if > 0: position of "const"
 		Idents []*Ident;
 		Typ Expr;
 		Vals Expr;
 	};
 	
 	TypeDecl struct {
-		Pos int;  // if > 0: position of "type"
+		Loc scanner.Location;  // if > 0: position of "type"
 		Ident *Ident;
 		Typ Expr;
 	};
 	
 	VarDecl struct {
-		Pos int;  // if > 0: position of "var"
+		Loc scanner.Location;  // if > 0: position of "var"
 		Idents []*Ident;
 		Typ Expr;
 		Vals Expr;
 	};
 
 	FuncDecl struct {
-		Pos int;  // position of "func"
+		Loc scanner.Location;  // location of "func"
 		Recv *Field;
 		Ident *Ident;
 		Sig *Signature;
@@ -477,10 +469,10 @@ type (
 	};
 	
 	DeclList struct {
-		Pos int;  // position of Tok
+		Loc scanner.Location;  // location of Tok
 		Tok int;
 		List []Decl;
-		End int;
+		End scanner.Location;
 	};
 )
 
@@ -509,21 +501,21 @@ func (d *DeclList) Visit(v DeclVisitor) { v.DoDeclList(d); }
 // Program
 
 type Comment struct {
-	Pos int;
+	Loc scanner.Location;
 	Text []byte;
 }
 
 
 type Program struct {
-	Pos int;  // tok is token.PACKAGE
+	Loc scanner.Location;  // tok is token.PACKAGE
 	Ident *Ident;
 	Decls []Decl;
 	Comments []*Comment;
 }
 
 
-func NewProgram(pos int) *Program {
+func NewProgram(loc scanner.Location) *Program {
 	p := new(Program);
-	p.Pos = pos;
+	p.Loc = loc;
 	return p;
 }
diff --git a/usr/gri/pretty/compilation.go b/usr/gri/pretty/compilation.go
index aa8ce109b2..9d650fb317 100644
--- a/usr/gri/pretty/compilation.go
+++ b/usr/gri/pretty/compilation.go
@@ -11,7 +11,7 @@ import (
 	"os";
 	Utils "utils";
 	Platform "platform";
-	Scanner "scanner";
+	"scanner";
 	Parser "parser";
 	AST "ast";
 	TypeChecker "typechecker";
@@ -35,23 +35,20 @@ type Flags struct {
 type errorHandler struct {
 	filename string;
 	src []byte;
-	nerrors int;
-	nwarnings int;
-	errpos int;
 	columns bool;
+	errline int;
+	nerrors int;
 }
 
 
 func (h *errorHandler) Init(filename string, src []byte, columns bool) {
 	h.filename = filename;
 	h.src = src;
-	h.nerrors = 0;
-	h.nwarnings = 0;
-	h.errpos = 0;
 	h.columns = columns;
 }
 
 
+/*
 // Compute (line, column) information for a given source position.
 func (h *errorHandler) LineCol(pos int) (line, col int) {
 	line = 1;
@@ -71,40 +68,30 @@ func (h *errorHandler) LineCol(pos int) (line, col int) {
 
 	return line, utf8.RuneCount(src[lpos : pos]);
 }
+*/
 
 
-func (h *errorHandler) ErrorMsg(pos int, msg string) {
-	print(h.filename, ":");
-	if pos >= 0 {
-		// print position
-		line, col := h.LineCol(pos);
-		print(line, ":");
-		if h.columns {
-			print(col, ":");
-		}
+func (h *errorHandler) ErrorMsg(loc scanner.Location, msg string) {
+	fmt.Printf("%s:%d:", h.filename, loc.Line);
+	if h.columns {
+		fmt.Printf("%d:", loc.Col);
 	}
-	print(" ", msg, "\n");
+	fmt.Printf(" %s\n", msg);
+
+	h.errline = loc.Line;
 
 	h.nerrors++;
-	h.errpos = pos;
-
 	if h.nerrors >= 10 {
 		sys.Exit(1);
 	}
 }
 
 
-func (h *errorHandler) Error(pos int, msg string) {
-	// only report errors that are sufficiently far away from the previous error
+func (h *errorHandler) Error(loc scanner.Location, msg string) {
+	// only report errors that are on a new line 
 	// in the hope to avoid most follow-up errors
-	const errdist = 20;
-	delta := pos - h.errpos;  // may be negative!
-	if delta < 0 {
-		delta = -delta;
-	}
-
-	if delta > errdist || h.nerrors == 0 /* always report first error */ {
-		h.ErrorMsg(pos, msg);
+	if loc.Line != h.errline {
+		h.ErrorMsg(loc, msg);
 	}
 }
 
@@ -119,7 +106,7 @@ func Compile(src_file string, flags *Flags) (*AST.Program, int) {
 	var err errorHandler;
 	err.Init(src_file, src, flags.Columns);
 
-	var scanner Scanner.Scanner;
+	var scanner scanner.Scanner;
 	scanner.Init(src, &err, true);
 
 	var parser Parser.Parser;
@@ -184,7 +171,7 @@ func addDeps(globalset map [string] bool, wset *vector.Vector, src_file string,
 				decl := prog.Decls[i];
 				panic();
 				/*
-				assert(decl.Tok == Scanner.IMPORT);
+				assert(decl.Tok == scanner.IMPORT);
 				if decl.List == nil {
 					printDep(localset, wset, decl);
 				} else {
diff --git a/usr/gri/pretty/parser.go b/usr/gri/pretty/parser.go
index 4d37c87adf..e80fb7e7be 100644
--- a/usr/gri/pretty/parser.go
+++ b/usr/gri/pretty/parser.go
@@ -16,36 +16,18 @@ import (
 	"fmt";
 	"vector";
 	"token";
+	"scanner";
 	"ast";
 )
 
 
-// An implementation of an ErrorHandler must be provided to the Parser.
-// If a syntax error is encountered, Error is called with the exact
-// token position (the byte position of the token in the source) and the
-// error message.
-//
-type ErrorHandler interface {
-	Error(pos int, msg string);
-}
-
-
-// An implementation of a Scanner must be provided to the Parser.
-// The parser calls Scan repeatedly to get a sequential stream of
-// tokens. The source end is indicated by token.EOF.
-//
-type Scanner interface {
-	Scan() (pos, tok int, lit []byte);
-}
-
-
 // A Parser holds the parser's internal state while processing
 // a given text. It can be allocated as part of another data
 // structure but must be initialized via Init before use.
 //
 type Parser struct {
-	scanner Scanner;
-	err ErrorHandler;
+	scanner *scanner.Scanner;
+	err scanner.ErrorHandler;
 
 	// Tracing/debugging
 	trace bool;
@@ -54,7 +36,7 @@ type Parser struct {
 	comments *vector.Vector;
 
 	// The next token
-	pos int;  // token source position
+	loc scanner.Location;  // token location
 	tok int;  // one token look-ahead
 	val []byte;  // token value
 
@@ -66,6 +48,11 @@ type Parser struct {
 };
 
 
+// When we don't have a location use noloc.
+// TODO make sure we always have a location.
+var noloc scanner.Location;
+
+
 // ----------------------------------------------------------------------------
 // Helper functions
 
@@ -105,23 +92,22 @@ func un/*trace*/(P *Parser) {
 
 
 func (P *Parser) next0() {
-	var val []byte;
-	P.pos, P.tok, P.val = P.scanner.Scan();
+	P.loc, P.tok, P.val = P.scanner.Scan();
 	P.opt_semi = false;
 
 	if P.trace {
 		P.printIndent();
 		switch P.tok {
 		case token.IDENT, token.INT, token.FLOAT, token.CHAR, token.STRING:
-			fmt.Printf("[%d] %s = %s\n", P.pos, token.TokenString(P.tok), P.val);
+			fmt.Printf("%d:%d: %s = %s\n", P.loc.Line, P.loc.Col, token.TokenString(P.tok), P.val);
 		case token.LPAREN:
 			// don't print '(' - screws up selection in terminal window
-			fmt.Printf("[%d] LPAREN\n", P.pos);
+			fmt.Printf("%d:%d: LPAREN\n", P.loc.Line, P.loc.Col);
 		case token.RPAREN:
 			// don't print ')' - screws up selection in terminal window
-			fmt.Printf("[%d] RPAREN\n", P.pos);
+			fmt.Printf("%d:%d: RPAREN\n", P.loc.Line, P.loc.Col);
 		default:
-			fmt.Printf("[%d] %s\n", P.pos, token.TokenString(P.tok));
+			fmt.Printf("%d:%d: %s\n", P.loc.Line, P.loc.Col, token.TokenString(P.tok));
 		}
 	}
 }
@@ -129,12 +115,12 @@ func (P *Parser) next0() {
 
 func (P *Parser) next() {
 	for P.next0(); P.tok == token.COMMENT; P.next0() {
-		P.comments.Push(&ast.Comment{P.pos, P.val});
+		P.comments.Push(&ast.Comment{P.loc, P.val});
 	}
 }
 
 
-func (P *Parser) Init(scanner Scanner, err ErrorHandler, trace bool) {
+func (P *Parser) Init(scanner *scanner.Scanner, err scanner.ErrorHandler, trace bool) {
 	P.scanner = scanner;
 	P.err = err;
 
@@ -148,8 +134,8 @@ func (P *Parser) Init(scanner Scanner, err ErrorHandler, trace bool) {
 }
 
 
-func (P *Parser) error(pos int, msg string) {
-	P.err.Error(pos, msg);
+func (P *Parser) error(loc scanner.Location, msg string) {
+	P.err.Error(loc, msg);
 }
 
 
@@ -159,7 +145,7 @@ func (P *Parser) expect(tok int) {
 		if token.IsLiteral(P.tok) {
 			msg += " " + string(P.val);
 		}
-		P.error(P.pos, msg);
+		P.error(P.loc, msg);
 	}
 	P.next();  // make progress in any case
 }
@@ -180,13 +166,13 @@ func (P *Parser) parseIdent() *ast.Ident {
 	}
 
 	if P.tok == token.IDENT {
-		x := &ast.Ident{P.pos, string(P.val)};
+		x := &ast.Ident{P.loc, string(P.val)};
 		P.next();
 		return x;
 	}
 
 	P.expect(token.IDENT);  // use expect() error handling
-	return &ast.Ident{P.pos, ""};
+	return &ast.Ident{P.loc, ""};
 }
 
 
@@ -200,14 +186,14 @@ func (P *Parser) parseIdentList(x ast.Expr) ast.Expr {
 		x = P.parseIdent();
 	}
 	for P.tok == token.COMMA {
-		pos := P.pos;
+		loc := P.loc;
 		P.next();
 		y := P.parseIdent();
 		if last == nil {
-			last = &ast.BinaryExpr{pos, token.COMMA, x, y};
+			last = &ast.BinaryExpr{loc, token.COMMA, x, y};
 			x = last;
 		} else {
-			last.Y = &ast.BinaryExpr{pos, token.COMMA, last.Y, y};
+			last.Y = &ast.BinaryExpr{loc, token.COMMA, last.Y, y};
 			last = last.Y.(*ast.BinaryExpr);
 		}
 	}
@@ -250,8 +236,8 @@ func (P *Parser) parseType() ast.Expr {
 
 	t := P.tryType();
 	if t == nil {
-		P.error(P.pos, "type expected");
-		t = &ast.BadExpr{P.pos};
+		P.error(P.loc, "type expected");
+		t = &ast.BadExpr{P.loc};
 	}
 
 	return t;
@@ -274,10 +260,10 @@ func (P *Parser) parseQualifiedIdent() ast.Expr {
 
 	var x ast.Expr = P.parseIdent();
 	for P.tok == token.PERIOD {
-		pos := P.pos;
+		loc := P.loc;
 		P.next();
 		y := P.parseIdent();
-		x = &ast.Selector{pos, x, y};
+		x = &ast.Selector{loc, x, y};
 	}
 
 	return x;
@@ -298,11 +284,11 @@ func (P *Parser) parseArrayType() *ast.ArrayType {
 		defer un(trace(P, "ArrayType"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.LBRACK);
 	var len ast.Expr;
 	if P.tok == token.ELLIPSIS {
-		len = &ast.Ellipsis{P.pos};
+		len = &ast.Ellipsis{P.loc};
 		P.next();
 	} else if P.tok != token.RBRACK {
 		len = P.parseExpression(1);
@@ -310,7 +296,7 @@ func (P *Parser) parseArrayType() *ast.ArrayType {
 	P.expect(token.RBRACK);
 	elt := P.parseType();
 
-	return &ast.ArrayType{pos, len, elt};
+	return &ast.ArrayType{loc, len, elt};
 }
 
 
@@ -319,7 +305,7 @@ func (P *Parser) parseChannelType() *ast.ChannelType {
 		defer un(trace(P, "ChannelType"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	mode := ast.FULL;
 	if P.tok == token.CHAN {
 		P.next();
@@ -334,15 +320,15 @@ func (P *Parser) parseChannelType() *ast.ChannelType {
 	}
 	val := P.parseVarType();
 
-	return &ast.ChannelType{pos, mode, val};
+	return &ast.ChannelType{loc, mode, val};
 }
 
 
 func (P *Parser) tryParameterType() ast.Expr {
 	if P.tok == token.ELLIPSIS {
-		pos := P.tok;
+		loc  := P.loc;
 		P.next();
-		return &ast.Ellipsis{pos};
+		return &ast.Ellipsis{loc};
 	}
 	return P.tryType();
 }
@@ -351,8 +337,8 @@ func (P *Parser) tryParameterType() ast.Expr {
 func (P *Parser) parseParameterType() ast.Expr {
 	typ := P.tryParameterType();
 	if typ == nil {
-		P.error(P.tok, "type expected");
-		typ = &ast.BadExpr{P.pos};
+		P.error(P.loc, "type expected");
+		typ = &ast.BadExpr{P.loc};
 	}
 	return typ;
 }
@@ -472,7 +458,7 @@ func (P *Parser) parseSignature() *ast.Signature {
 	}
 
 	params := P.parseParameters(true);  // TODO find better solution
-	//t.End = P.pos;
+	//t.End = P.loc;
 	result := P.parseResult();
 
 	return &ast.Signature{params, result};
@@ -484,11 +470,11 @@ func (P *Parser) parseFunctionType() *ast.FunctionType {
 		defer un(trace(P, "FunctionType"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.FUNC);
 	sig := P.parseSignature();
 	
-	return &ast.FunctionType{pos, sig};
+	return &ast.FunctionType{loc, sig};
 }
 
 
@@ -503,7 +489,7 @@ func (P *Parser) parseMethodSpec() *ast.Field {
 	if tmp, is_ident := x.(*ast.Ident); is_ident && (P.tok == token.COMMA || P.tok == token.LPAREN) {
 		// method(s)
 		idents = P.parseIdentList2(x);
-		typ = &ast.FunctionType{0, P.parseSignature()};
+		typ = &ast.FunctionType{noloc, P.parseSignature()};
 	} else {
 		// embedded interface
 		typ = x;
@@ -518,8 +504,8 @@ func (P *Parser) parseInterfaceType() *ast.InterfaceType {
 		defer un(trace(P, "InterfaceType"));
 	}
 
-	pos := P.pos;
-	end := 0;
+	loc := P.loc;
+	var end scanner.Location;
 	var methods []*ast.Field;
 
 	P.expect(token.INTERFACE);
@@ -534,7 +520,7 @@ func (P *Parser) parseInterfaceType() *ast.InterfaceType {
 			}
 		}
 
-		end = P.pos;
+		end = P.loc;
 		P.expect(token.RBRACE);
 		P.opt_semi = true;
 		
@@ -545,7 +531,7 @@ func (P *Parser) parseInterfaceType() *ast.InterfaceType {
 		}
 	}
 
-	return &ast.InterfaceType{pos, methods, end};
+	return &ast.InterfaceType{loc, methods, end};
 }
 
 
@@ -554,14 +540,14 @@ func (P *Parser) parseMapType() *ast.MapType {
 		defer un(trace(P, "MapType"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.MAP);
 	P.expect(token.LBRACK);
 	key := P.parseVarType();
 	P.expect(token.RBRACK);
 	val := P.parseVarType();
 
-	return &ast.MapType{pos, key, val};
+	return &ast.MapType{loc, key, val};
 }
 
 
@@ -602,7 +588,7 @@ func (P *Parser) parseFieldDecl() *ast.Field {
 			if ident, is_ident := list.At(i).(*ast.Ident); is_ident {
 				idents[i] = ident;
 			} else {
-				P.error(list.At(i).(ast.Expr).Pos(), "identifier expected");
+				P.error(list.At(i).(ast.Expr).Loc(), "identifier expected");
 			}
 		}
 	} else {
@@ -611,7 +597,7 @@ func (P *Parser) parseFieldDecl() *ast.Field {
 			// TODO should do more checks here
 			typ = list.At(0).(ast.Expr);
 		} else {
-			P.error(P.pos, "anonymous field expected");
+			P.error(P.loc, "anonymous field expected");
 		}
 	}
 	
@@ -624,8 +610,8 @@ func (P *Parser) parseStructType() ast.Expr {
 		defer un(trace(P, "StructType"));
 	}
 
-	pos := P.pos;
-	end := 0;
+	loc := P.loc;
+	var end scanner.Location;
 	var fields []*ast.Field;
 	
 	P.expect(token.STRUCT);
@@ -645,7 +631,7 @@ func (P *Parser) parseStructType() ast.Expr {
 			P.next();
 		}
 
-		end = P.pos;
+		end = P.loc;
 		P.expect(token.RBRACE);
 		P.opt_semi = true;
 
@@ -656,7 +642,7 @@ func (P *Parser) parseStructType() ast.Expr {
 		}
 	}
 
-	return ast.StructType{pos, fields, end};
+	return ast.StructType{loc, fields, end};
 }
 
 
@@ -665,11 +651,11 @@ func (P *Parser) parsePointerType() ast.Expr {
 		defer un(trace(P, "PointerType"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.MUL);
 	base := P.parseType();
 
-	return &ast.PointerType{pos, base};
+	return &ast.PointerType{loc, base};
 }
 
 
@@ -688,11 +674,11 @@ func (P *Parser) tryType() ast.Expr {
 	case token.STRUCT: return P.parseStructType();
 	case token.MUL: return P.parsePointerType();
 	case token.LPAREN:
-		pos := P.pos;
+		loc := P.loc;
 		P.next();
 		t := P.parseType();
 		P.expect(token.RPAREN);
-		return &ast.Group{pos, t};
+		return &ast.Group{loc, t};
 	}
 
 	// no type found
@@ -732,13 +718,13 @@ func (P *Parser) parseBlock(tok int) *ast.Block {
 		defer un(trace(P, "Block"));
 	}
 
-	b := ast.NewBlock(P.pos, tok);
+	b := ast.NewBlock(P.loc, tok);
 	P.expect(tok);
 
 	P.parseStatementList(b.List);
 	
 	if tok == token.LBRACE {
-		b.End = P.pos;
+		b.End = P.loc;
 		P.expect(token.RBRACE);
 		P.opt_semi = true;
 	}
@@ -757,14 +743,14 @@ func (P *Parser) parseExpressionList() ast.Expr {
 
 	x := P.parseExpression(1);
 	for first := true; P.tok == token.COMMA; {
-		pos := P.pos;
+		loc := P.loc;
 		P.next();
 		y := P.parseExpression(1);
 		if first {
-			x = &ast.BinaryExpr{pos, token.COMMA, x, y};
+			x = &ast.BinaryExpr{loc, token.COMMA, x, y};
 			first = false;
 		} else {
-			x.(*ast.BinaryExpr).Y = &ast.BinaryExpr{pos, token.COMMA, x.(*ast.BinaryExpr).Y, y};
+			x.(*ast.BinaryExpr).Y = &ast.BinaryExpr{loc, token.COMMA, x.(*ast.BinaryExpr).Y, y};
 		}
 	}
 
@@ -777,14 +763,14 @@ func (P *Parser) parseFunctionLit() ast.Expr {
 		defer un(trace(P, "FunctionLit"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.FUNC);
 	typ := P.parseSignature();
 	P.expr_lev++;
 	body := P.parseBlock(token.LBRACE);
 	P.expr_lev--;
 
-	return &ast.FunctionLit{pos, typ, body};
+	return &ast.FunctionLit{loc, typ, body};
 }
 
 
@@ -793,11 +779,11 @@ func (P *Parser) parseStringLit() ast.Expr {
 		defer un(trace(P, "StringLit"));
 	}
 
-	var x ast.Expr = &ast.BasicLit{P.pos, P.tok, P.val};
+	var x ast.Expr = &ast.BasicLit{P.loc, P.tok, P.val};
 	P.expect(token.STRING);  // always satisfied
 	
 	for P.tok == token.STRING {
-		y := &ast.BasicLit{P.pos, P.tok, P.val};
+		y := &ast.BasicLit{P.loc, P.tok, P.val};
 		P.next();
 		x = &ast.ConcatExpr{x, y};
 	}
@@ -816,7 +802,7 @@ func (P *Parser) parseOperand() ast.Expr {
 		return P.parseIdent();
 
 	case token.INT, token.FLOAT, token.CHAR:
-		x := &ast.BasicLit{P.pos, P.tok, P.val};
+		x := &ast.BasicLit{P.loc, P.tok, P.val};
 		P.next();
 		return x;
 		
@@ -824,13 +810,13 @@ func (P *Parser) parseOperand() ast.Expr {
 		return P.parseStringLit();
 
 	case token.LPAREN:
-		pos := P.pos;
+		loc := P.loc;
 		P.next();
 		P.expr_lev++;
 		x := P.parseExpression(1);
 		P.expr_lev--;
 		P.expect(token.RPAREN);
-		return &ast.Group{pos, x};
+		return &ast.Group{loc, x};
 
 	case token.FUNC:
 		return P.parseFunctionLit();
@@ -840,12 +826,12 @@ func (P *Parser) parseOperand() ast.Expr {
 		if t != nil {
 			return t;
 		} else {
-			P.error(P.pos, "operand expected");
+			P.error(P.loc, "operand expected");
 			P.next();  // make progress
 		}
 	}
 
-	return &ast.BadExpr{P.pos};
+	return &ast.BadExpr{P.loc};
 }
 
 
@@ -854,22 +840,22 @@ func (P *Parser) parseSelectorOrTypeGuard(x ast.Expr) ast.Expr {
 		defer un(trace(P, "SelectorOrTypeGuard"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.PERIOD);
 
 	if P.tok == token.IDENT {
-		x = &ast.Selector{pos, x, P.parseIdent()};
+		x = &ast.Selector{loc, x, P.parseIdent()};
 
 	} else {
 		P.expect(token.LPAREN);
 		var typ ast.Expr;
 		if P.tok == token.TYPE {
-			typ = &ast.TypeType{P.pos};
+			typ = &ast.TypeType{P.loc};
 			P.next();
 		} else {
 			typ = P.parseType();
 		}
-		x = &ast.TypeGuard{pos, x, typ};
+		x = &ast.TypeGuard{loc, x, typ};
 		P.expect(token.RPAREN);
 	}
 
@@ -882,14 +868,14 @@ func (P *Parser) parseIndex(x ast.Expr) ast.Expr {
 		defer un(trace(P, "IndexOrSlice"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.LBRACK);
 	P.expr_lev++;
 	i := P.parseExpression(0);
 	P.expr_lev--;
 	P.expect(token.RBRACK);
 
-	return &ast.Index{pos, x, i};
+	return &ast.Index{loc, x, i};
 }
 
 
@@ -898,7 +884,7 @@ func (P *Parser) parseBinaryExpr(prec1 int) ast.Expr
 func (P *Parser) parseCompositeElements(close int) ast.Expr {
 	x := P.parseExpression(0);
 	if P.tok == token.COMMA {
-		pos := P.pos;
+		loc := P.loc;
 		P.next();
 
 		// first element determines mode
@@ -913,24 +899,24 @@ func (P *Parser) parseCompositeElements(close int) ast.Expr {
 
 			if singles {
 				if t, is_binary := y.(*ast.BinaryExpr); is_binary && t.Tok == token.COLON {
-					P.error(t.X.Pos(), "single value expected; found pair");
+					P.error(t.X.Loc(), "single value expected; found pair");
 				}
 			} else {
 				if t, is_binary := y.(*ast.BinaryExpr); !is_binary || t.Tok != token.COLON {
-					P.error(y.Pos(), "key:value pair expected; found single value");
+					P.error(y.Loc(), "key:value pair expected; found single value");
 				}
 			}
 
 			if last == nil {
-				last = &ast.BinaryExpr{pos, token.COMMA, x, y};
+				last = &ast.BinaryExpr{loc, token.COMMA, x, y};
 				x = last;
 			} else {
-				last.Y = &ast.BinaryExpr{pos, token.COMMA, last.Y, y};
+				last.Y = &ast.BinaryExpr{loc, token.COMMA, last.Y, y};
 				last = last.Y.(*ast.BinaryExpr);
 			}
 
 			if P.tok == token.COMMA {
-				pos = P.pos;
+				loc = P.loc;
 				P.next();
 			} else {
 				break;
@@ -947,7 +933,7 @@ func (P *Parser) parseCallOrCompositeLit(f ast.Expr, open, close int) ast.Expr {
 		defer un(trace(P, "CallOrCompositeLit"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(open);
 	var args ast.Expr;
 	if P.tok != close {
@@ -955,7 +941,7 @@ func (P *Parser) parseCallOrCompositeLit(f ast.Expr, open, close int) ast.Expr {
 	}
 	P.expect(close);
 
-	return &ast.Call{pos, open, f, args};
+	return &ast.Call{loc, open, f, args};
 }
 
 
@@ -994,10 +980,10 @@ func (P *Parser) parseUnaryExpr() ast.Expr {
 
 	switch P.tok {
 	case token.ADD, token.SUB, token.MUL, token.NOT, token.XOR, token.ARROW, token.AND:
-		pos, tok := P.pos, P.tok;
+		loc, tok := P.loc, P.tok;
 		P.next();
 		y := P.parseUnaryExpr();
-		return &ast.UnaryExpr{pos, tok, y};
+		return &ast.UnaryExpr{loc, tok, y};
 		/*
 		if lit, ok := y.(*ast.TypeLit); ok && tok == token.MUL {
 			// pointer type
@@ -1005,7 +991,7 @@ func (P *Parser) parseUnaryExpr() ast.Expr {
 			t.Elt = lit.Typ;
 			return &ast.TypeLit{t};
 		} else {
-			return &ast.UnaryExpr{pos, tok, y};
+			return &ast.UnaryExpr{loc, tok, y};
 		}
 		*/
 	}
@@ -1022,10 +1008,10 @@ func (P *Parser) parseBinaryExpr(prec1 int) ast.Expr {
 	x := P.parseUnaryExpr();
 	for prec := token.Precedence(P.tok); prec >= prec1; prec-- {
 		for token.Precedence(P.tok) == prec {
-			pos, tok := P.pos, P.tok;
+			loc, tok := P.loc, P.tok;
 			P.next();
 			y := P.parseBinaryExpr(prec + 1);
-			x = &ast.BinaryExpr{pos, tok, x, y};
+			x = &ast.BinaryExpr{loc, tok, x, y};
 		}
 	}
 
@@ -1059,15 +1045,15 @@ func (P *Parser) parseSimpleStat(range_ok bool) ast.Stat {
 	switch P.tok {
 	case token.COLON:
 		// label declaration
-		pos := P.pos;
+		loc := P.loc;
 		P.next();  // consume ":"
 		P.opt_semi = true;
 		if ast.ExprLen(x) == 1 {
 			if label, is_ident := x.(*ast.Ident); is_ident {
-				return &ast.LabelDecl{pos, label};
+				return &ast.LabelDecl{loc, label};
 			}
 		}
-		P.error(x.Pos(), "illegal label declaration");
+		P.error(x.Loc(), "illegal label declaration");
 		return nil;
 
 	case
@@ -1076,38 +1062,38 @@ func (P *Parser) parseSimpleStat(range_ok bool) ast.Stat {
 		token.REM_ASSIGN, token.AND_ASSIGN, token.OR_ASSIGN,
 		token.XOR_ASSIGN, token.SHL_ASSIGN, token.SHR_ASSIGN:
 		// declaration/assignment
-		pos, tok := P.pos, P.tok;
+		loc, tok := P.loc, P.tok;
 		P.next();
 		var y ast.Expr;
 		if range_ok && P.tok == token.RANGE {
-			range_pos := P.pos;
+			range_loc := P.loc;
 			P.next();
-			y = &ast.UnaryExpr{range_pos, token.RANGE, P.parseExpression(1)};
+			y = &ast.UnaryExpr{range_loc, token.RANGE, P.parseExpression(1)};
 			if tok != token.DEFINE && tok != token.ASSIGN {
-				P.error(pos, "expected '=' or ':=', found '" + token.TokenString(tok) + "'");
+				P.error(loc, "expected '=' or ':=', found '" + token.TokenString(tok) + "'");
 			}
 		} else {
 			y = P.parseExpressionList();
 			if xl, yl := ast.ExprLen(x), ast.ExprLen(y); xl > 1 && yl > 1 && xl != yl {
-				P.error(x.Pos(), "arity of lhs doesn't match rhs");
+				P.error(x.Loc(), "arity of lhs doesn't match rhs");
 			}
 		}
 		// TODO changed ILLEGAL -> NONE
-		return &ast.ExpressionStat{x.Pos(), token.ILLEGAL, &ast.BinaryExpr{pos, tok, x, y}};
+		return &ast.ExpressionStat{x.Loc(), token.ILLEGAL, &ast.BinaryExpr{loc, tok, x, y}};
 
 	default:
 		if ast.ExprLen(x) != 1 {
-			P.error(x.Pos(), "only one expression allowed");
+			P.error(x.Loc(), "only one expression allowed");
 		}
 
 		if P.tok == token.INC || P.tok == token.DEC {
-			s := &ast.ExpressionStat{P.pos, P.tok, x};
+			s := &ast.ExpressionStat{P.loc, P.tok, x};
 			P.next();  // consume "++" or "--"
 			return s;
 		}
 
 		// TODO changed ILLEGAL -> NONE
-		return &ast.ExpressionStat{x.Pos(), token.ILLEGAL, x};
+		return &ast.ExpressionStat{x.Loc(), token.ILLEGAL, x};
 	}
 
 	unreachable();
@@ -1120,9 +1106,9 @@ func (P *Parser) parseInvocationStat(keyword int) *ast.ExpressionStat {
 		defer un(trace(P, "InvocationStat"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(keyword);
-	return &ast.ExpressionStat{pos, keyword, P.parseExpression(1)};
+	return &ast.ExpressionStat{loc, keyword, P.parseExpression(1)};
 }
 
 
@@ -1131,14 +1117,14 @@ func (P *Parser) parseReturnStat() *ast.ExpressionStat {
 		defer un(trace(P, "ReturnStat"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.RETURN);
 	var x ast.Expr;
 	if P.tok != token.SEMICOLON && P.tok != token.RBRACE {
 		x = P.parseExpressionList();
 	}
 
-	return &ast.ExpressionStat{pos, token.RETURN, x};
+	return &ast.ExpressionStat{loc, token.RETURN, x};
 }
 
 
@@ -1147,7 +1133,7 @@ func (P *Parser) parseControlFlowStat(tok int) *ast.ControlFlowStat {
 		defer un(trace(P, "ControlFlowStat"));
 	}
 
-	s := &ast.ControlFlowStat{P.pos, tok, nil};
+	s := &ast.ControlFlowStat{P.loc, tok, nil};
 	P.expect(tok);
 	if tok != token.FALLTHROUGH && P.tok == token.IDENT {
 		s.Label = P.parseIdent();
@@ -1185,7 +1171,7 @@ func (P *Parser) parseControlClause(isForStat bool) (init ast.Stat, expr ast.Exp
 				if s, is_expr_stat := init.(*ast.ExpressionStat); is_expr_stat {
 					expr, init = s.Expr, nil;
 				} else {
-					P.error(0, "illegal control clause");
+					P.error(noloc, "illegal control clause");
 				}
 			}
 		}
@@ -1201,7 +1187,7 @@ func (P *Parser) parseIfStat() *ast.IfStat {
 		defer un(trace(P, "IfStat"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.IF);
 	init, cond, dummy := P.parseControlClause(false);
 	body := P.parseBlock(token.LBRACE);
@@ -1211,7 +1197,7 @@ func (P *Parser) parseIfStat() *ast.IfStat {
 		else_ = P.parseStatement();
 	}
 
-	return &ast.IfStat{pos, init, cond, body, else_};
+	return &ast.IfStat{loc, init, cond, body, else_};
 }
 
 
@@ -1220,12 +1206,12 @@ func (P *Parser) parseForStat() *ast.ForStat {
 		defer un(trace(P, "ForStat"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.FOR);
 	init, cond, post := P.parseControlClause(true);
 	body := P.parseBlock(token.LBRACE);
 
-	return &ast.ForStat{pos, init, cond, post, body};
+	return &ast.ForStat{loc, init, cond, post, body};
 }
 
 
@@ -1235,7 +1221,7 @@ func (P *Parser) parseCaseClause() *ast.CaseClause {
 	}
 
 	// SwitchCase
-	pos := P.pos;
+	loc := P.loc;
 	var expr ast.Expr;
 	if P.tok == token.CASE {
 		P.next();
@@ -1244,7 +1230,7 @@ func (P *Parser) parseCaseClause() *ast.CaseClause {
 		P.expect(token.DEFAULT);
 	}
 
-	return &ast.CaseClause{pos, expr, P.parseBlock(token.COLON)};
+	return &ast.CaseClause{loc, expr, P.parseBlock(token.COLON)};
 }
 
 
@@ -1253,19 +1239,19 @@ func (P *Parser) parseSwitchStat() *ast.SwitchStat {
 		defer un(trace(P, "SwitchStat"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.SWITCH);
 	init, tag, post := P.parseControlClause(false);
-	body := ast.NewBlock(P.pos, token.LBRACE);
+	body := ast.NewBlock(P.loc, token.LBRACE);
 	P.expect(token.LBRACE);
 	for P.tok != token.RBRACE && P.tok != token.EOF {
 		body.List.Push(P.parseCaseClause());
 	}
-	body.End = P.pos;
+	body.End = P.loc;
 	P.expect(token.RBRACE);
 	P.opt_semi = true;
 
-	return &ast.SwitchStat{pos, init, tag, body};
+	return &ast.SwitchStat{loc, init, tag, body};
 }
 
 
@@ -1275,17 +1261,17 @@ func (P *Parser) parseCommClause() *ast.CaseClause {
 	}
 
 	// CommCase
-	pos := P.pos;
+	loc := P.loc;
 	var expr ast.Expr;
 	if P.tok == token.CASE {
 		P.next();
 		x := P.parseExpression(1);
 		if P.tok == token.ASSIGN || P.tok == token.DEFINE {
-			pos, tok := P.pos, P.tok;
+			loc, tok := P.loc, P.tok;
 			P.next();
 			if P.tok == token.ARROW {
 				y := P.parseExpression(1);
-				x = &ast.BinaryExpr{pos, tok, x, y};
+				x = &ast.BinaryExpr{loc, tok, x, y};
 			} else {
 				P.expect(token.ARROW);  // use expect() error handling
 			}
@@ -1295,7 +1281,7 @@ func (P *Parser) parseCommClause() *ast.CaseClause {
 		P.expect(token.DEFAULT);
 	}
 
-	return &ast.CaseClause{pos, expr, P.parseBlock(token.COLON)};
+	return &ast.CaseClause{loc, expr, P.parseBlock(token.COLON)};
 }
 
 
@@ -1304,18 +1290,18 @@ func (P *Parser) parseSelectStat() *ast.SelectStat {
 		defer un(trace(P, "SelectStat"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.SELECT);
-	body := ast.NewBlock(P.pos, token.LBRACE);
+	body := ast.NewBlock(P.loc, token.LBRACE);
 	P.expect(token.LBRACE);
 	for P.tok != token.RBRACE && P.tok != token.EOF {
 		body.List.Push(P.parseCommClause());
 	}
-	body.End = P.pos;
+	body.End = P.loc;
 	P.expect(token.RBRACE);
 	P.opt_semi = true;
 
-	return &ast.SelectStat{pos, body};
+	return &ast.SelectStat{loc, body};
 }
 
 
@@ -1355,26 +1341,26 @@ func (P *Parser) parseStatement() ast.Stat {
 		return P.parseSelectStat();
 	case token.SEMICOLON:
 		// don't consume the ";", it is the separator following the empty statement
-		return &ast.EmptyStat{P.pos};
+		return &ast.EmptyStat{P.loc};
 	}
 
 	// no statement found
-	P.error(P.pos, "statement expected");
-	return &ast.BadStat{P.pos};
+	P.error(P.loc, "statement expected");
+	return &ast.BadStat{P.loc};
 }
 
 
 // ----------------------------------------------------------------------------
 // Declarations
 
-func (P *Parser) parseImportSpec(pos int) *ast.ImportDecl {
+func (P *Parser) parseImportSpec(loc scanner.Location) *ast.ImportDecl {
 	if P.trace {
 		defer un(trace(P, "ImportSpec"));
 	}
 
 	var ident *ast.Ident;
 	if P.tok == token.PERIOD {
-		P.error(P.pos, `"import ." not yet handled properly`);
+		P.error(P.loc, `"import ." not yet handled properly`);
 		P.next();
 	} else if P.tok == token.IDENT {
 		ident = P.parseIdent();
@@ -1387,11 +1373,11 @@ func (P *Parser) parseImportSpec(pos int) *ast.ImportDecl {
 		P.expect(token.STRING);  // use expect() error handling
 	}
 	
-	return &ast.ImportDecl{pos, ident, path};
+	return &ast.ImportDecl{loc, ident, path};
 }
 
 
-func (P *Parser) parseConstSpec(pos int) *ast.ConstDecl {
+func (P *Parser) parseConstSpec(loc scanner.Location) *ast.ConstDecl {
 	if P.trace {
 		defer un(trace(P, "ConstSpec"));
 	}
@@ -1404,11 +1390,11 @@ func (P *Parser) parseConstSpec(pos int) *ast.ConstDecl {
 		vals = P.parseExpressionList();
 	}
 	
-	return &ast.ConstDecl{pos, idents, typ, vals};
+	return &ast.ConstDecl{loc, idents, typ, vals};
 }
 
 
-func (P *Parser) parseTypeSpec(pos int) *ast.TypeDecl {
+func (P *Parser) parseTypeSpec(loc scanner.Location) *ast.TypeDecl {
 	if P.trace {
 		defer un(trace(P, "TypeSpec"));
 	}
@@ -1416,11 +1402,11 @@ func (P *Parser) parseTypeSpec(pos int) *ast.TypeDecl {
 	ident := P.parseIdent();
 	typ := P.parseType();
 	
-	return &ast.TypeDecl{pos, ident, typ};
+	return &ast.TypeDecl{loc, ident, typ};
 }
 
 
-func (P *Parser) parseVarSpec(pos int) *ast.VarDecl {
+func (P *Parser) parseVarSpec(loc scanner.Location) *ast.VarDecl {
 	if P.trace {
 		defer un(trace(P, "VarSpec"));
 	}
@@ -1439,16 +1425,16 @@ func (P *Parser) parseVarSpec(pos int) *ast.VarDecl {
 		}
 	}
 	
-	return &ast.VarDecl{pos, idents, typ, vals};
+	return &ast.VarDecl{loc, idents, typ, vals};
 }
 
 
-func (P *Parser) parseSpec(pos, keyword int) ast.Decl {
+func (P *Parser) parseSpec(loc scanner.Location, keyword int) ast.Decl {
 	switch keyword {
-	case token.IMPORT: return P.parseImportSpec(pos);
-	case token.CONST: return P.parseConstSpec(pos);
-	case token.TYPE: return P.parseTypeSpec(pos);
-	case token.VAR: return P.parseVarSpec(pos);
+	case token.IMPORT: return P.parseImportSpec(loc);
+	case token.CONST: return P.parseConstSpec(loc);
+	case token.TYPE: return P.parseTypeSpec(loc);
+	case token.VAR: return P.parseVarSpec(loc);
 	}
 	
 	unreachable();
@@ -1461,20 +1447,20 @@ func (P *Parser) parseDecl(keyword int) ast.Decl {
 		defer un(trace(P, "Decl"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(keyword);
 	if P.tok == token.LPAREN {
 		P.next();
 		list := vector.New(0);
 		for P.tok != token.RPAREN && P.tok != token.EOF {
-			list.Push(P.parseSpec(0, keyword));
+			list.Push(P.parseSpec(noloc, keyword));
 			if P.tok == token.SEMICOLON {
 				P.next();
 			} else {
 				break;
 			}
 		}
-		end := P.pos;
+		end := P.loc;
 		P.expect(token.RPAREN);
 		P.opt_semi = true;
 		
@@ -1484,10 +1470,10 @@ func (P *Parser) parseDecl(keyword int) ast.Decl {
 			decls[i] = list.At(i).(ast.Decl);
 		}
 		
-		return &ast.DeclList{pos, keyword, decls, end};
+		return &ast.DeclList{loc, keyword, decls, end};
 	}
 
-	return P.parseSpec(pos, keyword);
+	return P.parseSpec(loc, keyword);
 }
 
 
@@ -1505,17 +1491,17 @@ func (P *Parser) parseFunctionDecl() *ast.FuncDecl {
 		defer un(trace(P, "FunctionDecl"));
 	}
 
-	pos := P.pos;
+	loc := P.loc;
 	P.expect(token.FUNC);
 
 	var recv *ast.Field;
 	if P.tok == token.LPAREN {
-		pos := P.pos;
+		loc := P.loc;
 		tmp := P.parseParameters(true);
 		if len(tmp) == 1 {
 			recv = tmp[0];
 		} else {
-			P.error(pos, "must have exactly one receiver");
+			P.error(loc, "must have exactly one receiver");
 		}
 	}
 
@@ -1527,7 +1513,7 @@ func (P *Parser) parseFunctionDecl() *ast.FuncDecl {
 		body = P.parseBlock(token.LBRACE);
 	}
 
-	return &ast.FuncDecl{pos, recv, ident, sig, body};
+	return &ast.FuncDecl{loc, recv, ident, sig, body};
 }
 
 
@@ -1543,10 +1529,10 @@ func (P *Parser) parseDeclaration() ast.Decl {
 		return P.parseFunctionDecl();
 	}
 	
-	pos := P.pos;
-	P.error(pos, "declaration expected");
+	loc := P.loc;
+	P.error(loc, "declaration expected");
 	P.next();  // make progress
-	return &ast.BadDecl{pos};
+	return &ast.BadDecl{loc};
 }
 
 
@@ -1626,7 +1612,7 @@ func (P *Parser) ParseProgram() *ast.Program {
 		defer un(trace(P, "Program"));
 	}
 
-	p := ast.NewProgram(P.pos);
+	p := ast.NewProgram(P.loc);
 	p.Ident = P.ParsePackageClause();
 
 	// package body
diff --git a/usr/gri/pretty/printer.go b/usr/gri/pretty/printer.go
index 54580f90ab..57d7809f98 100644
--- a/usr/gri/pretty/printer.go
+++ b/usr/gri/pretty/printer.go
@@ -12,13 +12,14 @@ import (
 	"flag";
 	"fmt";
 	"strings";
-	Utils "utils";
+	"utils";
 	"token";
+	"scanner";
 	"ast";
 	"template";
 	"utf8";
 	"unicode";
-	SymbolTable "symboltable";
+	"symboltable";
 )
 
 var (
@@ -37,6 +38,11 @@ var (
 )
 
 
+// When we don't have a location use noloc.
+// TODO make sure we always have a location.
+var noloc scanner.Location;
+
+
 // ----------------------------------------------------------------------------
 // Elementary support
 
@@ -118,7 +124,7 @@ func (P *Printer) HasComment(pos int) bool {
 func (P *Printer) NextComment() {
 	P.cindex++;
 	if P.comments != nil && P.cindex < len(P.comments) {
-		P.cpos = P.comments[P.cindex].Pos;
+		P.cpos = P.comments[P.cindex].Loc.Pos;
 	} else {
 		P.cpos = 1<<30;  // infinite
 	}
@@ -204,8 +210,9 @@ func (P *Printer) Newline(n int) {
 }
 
 
-func (P *Printer) TaggedString(pos int, tag, s, endtag string) {
+func (P *Printer) TaggedString(loc scanner.Location, tag, s, endtag string) {
 	// use estimate for pos if we don't have one
+	pos := loc.Pos;
 	if pos == 0 {
 		pos = P.lastpos;
 	}
@@ -372,19 +379,19 @@ func (P *Printer) TaggedString(pos int, tag, s, endtag string) {
 }
 
 
-func (P *Printer) String(pos int, s string) {
-	P.TaggedString(pos, "", s, "");
+func (P *Printer) String(loc scanner.Location, s string) {
+	P.TaggedString(loc, "", s, "");
 }
 
 
-func (P *Printer) Token(pos int, tok int) {
-	P.String(pos, token.TokenString(tok));
+func (P *Printer) Token(loc scanner.Location, tok int) {
+	P.String(loc, token.TokenString(tok));
 	//P.TaggedString(pos, "<b>", token.TokenString(tok), "</b>");
 }
 
 
-func (P *Printer) Error(pos int, tok int, msg string) {
-	fmt.Printf("\ninternal printing error: pos = %d, tok = %s, %s\n", pos, token.TokenString(tok), msg);
+func (P *Printer) Error(loc scanner.Location, tok int, msg string) {
+	fmt.Printf("\ninternal printing error: pos = %d, tok = %s, %s\n", loc.Pos, token.TokenString(tok), msg);
 	panic();
 }
 
@@ -393,34 +400,34 @@ func (P *Printer) Error(pos int, tok int, msg string) {
 // HTML support
 
 func (P *Printer) HtmlIdentifier(x *ast.Ident) {
-	P.String(x.Pos_, x.Str);
+	P.String(x.Loc_, x.Str);
 	/*
 	obj := x.Obj;
-	if P.html && obj.Kind != SymbolTable.NONE {
+	if P.html && obj.Kind != symbolTable.NONE {
 		// depending on whether we have a declaration or use, generate different html
 		// - no need to htmlEscape ident
-		id := Utils.IntToString(obj.Id, 10);
-		if x.Pos_ == obj.Pos {
+		id := utils.IntToString(obj.Id, 10);
+		if x.Loc_ == obj.Pos {
 			// probably the declaration of x
-			P.TaggedString(x.Pos_, `<a name="id` + id + `">`, obj.Ident, `</a>`);
+			P.TaggedString(x.Loc_, `<a name="id` + id + `">`, obj.Ident, `</a>`);
 		} else {
 			// probably not the declaration of x
-			P.TaggedString(x.Pos_, `<a href="#id` + id + `">`, obj.Ident, `</a>`);
+			P.TaggedString(x.Loc_, `<a href="#id` + id + `">`, obj.Ident, `</a>`);
 		}
 	} else {
-		P.String(x.Pos_, obj.Ident);
+		P.String(x.Loc_, obj.Ident);
 	}
 	*/
 }
 
 
-func (P *Printer) HtmlPackageName(pos int, name string) {
+func (P *Printer) HtmlPackageName(loc scanner.Location, name string) {
 	if P.html {
 		sname := name[1 : len(name)-1];  // strip quotes  TODO do this elsewhere eventually
 		// TODO CAPITAL HACK BELOW FIX THIS
-		P.TaggedString(pos, `"<a href="/src/lib/` + sname + `.go">`, sname, `</a>"`);
+		P.TaggedString(loc, `"<a href="/src/lib/` + sname + `.go">`, sname, `</a>"`);
 	} else {
-		P.String(pos, name);
+		P.String(loc, name);
 	}
 }
 
@@ -433,7 +440,7 @@ func (P *Printer) Expr(x ast.Expr)
 func (P *Printer) Idents(list []*ast.Ident) {
 	for i, x := range list {
 		if i > 0 {
-			P.Token(0, token.COMMA);
+			P.Token(noloc, token.COMMA);
 			P.separator = blank;
 			P.state = inside_list;
 		}
@@ -443,7 +450,7 @@ func (P *Printer) Idents(list []*ast.Ident) {
 
 
 func (P *Printer) Parameters(list []*ast.Field) {
-	P.Token(0, token.LPAREN);
+	P.Token(noloc, token.LPAREN);
 	if len(list) > 0 {
 		for i, par := range list {
 			if i > 0 {
@@ -456,7 +463,7 @@ func (P *Printer) Parameters(list []*ast.Field) {
 			P.Expr(par.Typ);
 		}
 	}
-	P.Token(0, token.RPAREN);
+	P.Token(noloc, token.RPAREN);
 }
 
 
@@ -482,10 +489,10 @@ func (P *Printer) Signature(sig *ast.Signature) {
 }
 
 
-func (P *Printer) Fields(list []*ast.Field, end int, is_interface bool) {
+func (P *Printer) Fields(list []*ast.Field, end scanner.Location, is_interface bool) {
 	P.state = opening_scope;
 	P.separator = blank;
-	P.Token(0, token.LBRACE);
+	P.Token(noloc, token.LBRACE);
 
 	if len(list) > 0 {
 		P.newlines = 1;
@@ -529,7 +536,7 @@ func (P *Printer) Expr1(x ast.Expr, prec1 int)
 
 
 func (P *Printer) DoBadExpr(x *ast.BadExpr) {
-	P.String(0, "BadExpr");
+	P.String(noloc, "BadExpr");
 }
 
 
@@ -542,22 +549,22 @@ func (P *Printer) DoBinaryExpr(x *ast.BinaryExpr) {
 	if x.Tok == token.COMMA {
 		// (don't use binary expression printing because of different spacing)
 		P.Expr(x.X);
-		P.Token(x.Pos_, token.COMMA);
+		P.Token(x.Loc_, token.COMMA);
 		P.separator = blank;
 		P.state = inside_list;
 		P.Expr(x.Y);
 	} else {
 		prec := token.Precedence(x.Tok);
 		if prec < P.prec {
-			P.Token(0, token.LPAREN);
+			P.Token(noloc, token.LPAREN);
 		}
 		P.Expr1(x.X, prec);
 		P.separator = blank;
-		P.Token(x.Pos_, x.Tok);
+		P.Token(x.Loc_, x.Tok);
 		P.separator = blank;
 		P.Expr1(x.Y, prec);
 		if prec < P.prec {
-			P.Token(0, token.RPAREN);
+			P.Token(noloc, token.RPAREN);
 		}
 	}
 }
@@ -566,15 +573,15 @@ func (P *Printer) DoBinaryExpr(x *ast.BinaryExpr) {
 func (P *Printer) DoUnaryExpr(x *ast.UnaryExpr) {
 	prec := token.UnaryPrec;
 	if prec < P.prec {
-		P.Token(0, token.LPAREN);
+		P.Token(noloc, token.LPAREN);
 	}
-	P.Token(x.Pos_, x.Tok);
+	P.Token(x.Loc_, x.Tok);
 	if x.Tok == token.RANGE {
 		P.separator = blank;
 	}
 	P.Expr1(x.X, prec);
 	if prec < P.prec {
-		P.Token(0, token.RPAREN);
+		P.Token(noloc, token.RPAREN);
 	}
 }
 
@@ -588,12 +595,12 @@ func (P *Printer) DoConcatExpr(x *ast.ConcatExpr) {
 
 func (P *Printer) DoBasicLit(x *ast.BasicLit) {
 	// TODO get rid of string conversion here
-	P.String(x.Pos_, string(x.Val));
+	P.String(x.Loc_, string(x.Val));
 }
 
 
 func (P *Printer) DoFunctionLit(x *ast.FunctionLit) {
-	P.Token(x.Pos_, token.FUNC);
+	P.Token(x.Loc_, token.FUNC);
 	P.Signature(x.Typ);
 	P.separator = blank;
 	P.Block(x.Body, true);
@@ -602,90 +609,90 @@ func (P *Printer) DoFunctionLit(x *ast.FunctionLit) {
 
 
 func (P *Printer) DoGroup(x *ast.Group) {
-	P.Token(x.Pos_, token.LPAREN);
+	P.Token(x.Loc_, token.LPAREN);
 	P.Expr(x.X);
-	P.Token(0, token.RPAREN);
+	P.Token(noloc, token.RPAREN);
 }
 
 
 func (P *Printer) DoSelector(x *ast.Selector) {
 	P.Expr1(x.X, token.HighestPrec);
-	P.Token(x.Pos_, token.PERIOD);
+	P.Token(x.Loc_, token.PERIOD);
 	P.Expr1(x.Sel, token.HighestPrec);
 }
 
 
 func (P *Printer) DoTypeGuard(x *ast.TypeGuard) {
 	P.Expr1(x.X, token.HighestPrec);
-	P.Token(x.Pos_, token.PERIOD);
-	P.Token(0, token.LPAREN);
+	P.Token(x.Loc_, token.PERIOD);
+	P.Token(noloc, token.LPAREN);
 	P.Expr(x.Typ);
-	P.Token(0, token.RPAREN);
+	P.Token(noloc, token.RPAREN);
 }
 
 
 func (P *Printer) DoIndex(x *ast.Index) {
 	P.Expr1(x.X, token.HighestPrec);
-	P.Token(x.Pos_, token.LBRACK);
+	P.Token(x.Loc_, token.LBRACK);
 	P.Expr1(x.I, 0);
-	P.Token(0, token.RBRACK);
+	P.Token(noloc, token.RBRACK);
 }
 
 
 func (P *Printer) DoCall(x *ast.Call) {
 	P.Expr1(x.F, token.HighestPrec);
-	P.Token(x.Pos_, x.Tok);
+	P.Token(x.Loc_, x.Tok);
 	P.Expr(x.Args);
 	switch x.Tok {
-	case token.LPAREN: P.Token(0, token.RPAREN);
-	case token.LBRACE: P.Token(0, token.RBRACE);
+	case token.LPAREN: P.Token(noloc, token.RPAREN);
+	case token.LBRACE: P.Token(noloc, token.RBRACE);
 	}
 }
 
 
 func (P *Printer) DoEllipsis(x *ast.Ellipsis) {
-	P.Token(x.Pos_, token.ELLIPSIS);
+	P.Token(x.Loc_, token.ELLIPSIS);
 }
 
 
 func (P *Printer) DoArrayType(x *ast.ArrayType) {
-	P.Token(x.Pos_, token.LBRACK);
+	P.Token(x.Loc_, token.LBRACK);
 	if x.Len != nil {
 		P.Expr(x.Len);
 	}
-	P.Token(0, token.RBRACK);
+	P.Token(noloc, token.RBRACK);
 	P.Expr(x.Elt);
 }
 
 
 func (P *Printer) DoTypeType(x *ast.TypeType) {
-	P.Token(x.Pos_, token.TYPE);
+	P.Token(x.Loc_, token.TYPE);
 }
 
 
 func (P *Printer) DoStructType(x *ast.StructType) {
-	P.Token(x.Pos_, token.STRUCT);
-	if x.End > 0 {
+	P.Token(x.Loc_, token.STRUCT);
+	if x.End.Pos > 0 {
 		P.Fields(x.Fields, x.End, false);
 	}
 }
 
 
 func (P *Printer) DoPointerType(x *ast.PointerType) {
-	P.Token(x.Pos_, token.MUL);
+	P.Token(x.Loc_, token.MUL);
 	P.Expr(x.Base);
 }
 
 
 func (P *Printer) DoFunctionType(x *ast.FunctionType) {
-	P.Token(x.Pos_, token.FUNC);
+	P.Token(x.Loc_, token.FUNC);
 	P.Signature(x.Sig);
 }
 
 
 func (P *Printer) DoInterfaceType(x *ast.InterfaceType) {
-	P.Token(x.Pos_, token.INTERFACE);
-	if x.End > 0 {
+	P.Token(x.Loc_, token.INTERFACE);
+	if x.End.Pos > 0 {
 		P.Fields(x.Methods, x.End, true);
 	}
 }
@@ -697,11 +704,11 @@ func (P *Printer) DoSliceType(x *ast.SliceType) {
 
 
 func (P *Printer) DoMapType(x *ast.MapType) {
-	P.Token(x.Pos_, token.MAP);
+	P.Token(x.Loc_, token.MAP);
 	P.separator = blank;
-	P.Token(0, token.LBRACK);
+	P.Token(noloc, token.LBRACK);
 	P.Expr(x.Key);
-	P.Token(0, token.RBRACK);
+	P.Token(noloc, token.RBRACK);
 	P.Expr(x.Val);
 }
 
@@ -709,14 +716,14 @@ func (P *Printer) DoMapType(x *ast.MapType) {
 func (P *Printer) DoChannelType(x *ast.ChannelType) {
 	switch x.Mode {
 	case ast.FULL:
-		P.Token(x.Pos_, token.CHAN);
+		P.Token(x.Loc_, token.CHAN);
 	case ast.RECV:
-		P.Token(x.Pos_, token.ARROW);
-		P.Token(0, token.CHAN);
+		P.Token(x.Loc_, token.ARROW);
+		P.Token(noloc, token.CHAN);
 	case ast.SEND:
-		P.Token(x.Pos_, token.CHAN);
+		P.Token(x.Loc_, token.CHAN);
 		P.separator = blank;
-		P.Token(0, token.ARROW);
+		P.Token(noloc, token.ARROW);
 	}
 	P.separator = blank;
 	P.Expr(x.Val);
@@ -767,7 +774,7 @@ func (P *Printer) StatementList(list *vector.Vector) {
 
 func (P *Printer) Block(b *ast.Block, indent bool) {
 	P.state = opening_scope;
-	P.Token(b.Pos, b.Tok);
+	P.Token(b.Loc, b.Tok);
 	if !indent {
 		P.indentation--;
 	}
@@ -783,7 +790,7 @@ func (P *Printer) Block(b *ast.Block, indent bool) {
 		P.Token(b.End, token.RBRACE);
 		P.opt_semi = true;
 	} else {
-		P.String(0, "");  // process closing_scope state transition!
+		P.String(noloc, "");  // process closing_scope state transition!
 	}
 }
 
@@ -798,7 +805,7 @@ func (P *Printer) DoBadStat(s *ast.BadStat) {
 func (P *Printer) DoLabelDecl(s *ast.LabelDecl) {
 	P.indentation--;
 	P.Expr(s.Label);
-	P.Token(s.Pos, token.COLON);
+	P.Token(s.Loc, token.COLON);
 	// TODO not quite correct:
 	// - we must not print this optional semicolon, as it may invalidate code.
 	// - this will change once the AST reflects the LabelStatement change
@@ -818,15 +825,15 @@ func (P *Printer) DoExpressionStat(s *ast.ExpressionStat) {
 		P.Expr(s.Expr);
 	case token.INC, token.DEC:
 		P.Expr(s.Expr);
-		P.Token(s.Pos, s.Tok);
+		P.Token(s.Loc, s.Tok);
 	case token.RETURN, token.GO, token.DEFER:
-		P.Token(s.Pos, s.Tok);
+		P.Token(s.Loc, s.Tok);
 		if s.Expr != nil {
 			P.separator = blank;
 			P.Expr(s.Expr);
 		}
 	default:
-		P.Error(s.Pos, s.Tok, "DoExpressionStat");
+		P.Error(s.Loc, s.Tok, "DoExpressionStat");
 		unreachable();
 	}
 }
@@ -851,14 +858,14 @@ func (P *Printer) ControlClause(isForStat bool, init ast.Stat, expr ast.Expr, po
 			P.Stat(init);
 			P.separator = none;
 		}
-		P.Token(0, token.SEMICOLON);
+		P.Token(noloc, token.SEMICOLON);
 		P.separator = blank;
 		if expr != nil {
 			P.Expr(expr);
 			P.separator = none;
 		}
 		if isForStat {
-			P.Token(0, token.SEMICOLON);
+			P.Token(noloc, token.SEMICOLON);
 			P.separator = blank;
 			if post != nil {
 				P.Stat(post);
@@ -870,12 +877,12 @@ func (P *Printer) ControlClause(isForStat bool, init ast.Stat, expr ast.Expr, po
 
 
 func (P *Printer) DoIfStat(s *ast.IfStat) {
-	P.Token(s.Pos, token.IF);
+	P.Token(s.Loc, token.IF);
 	P.ControlClause(false, s.Init, s.Cond, nil);
 	P.Block(s.Body, true);
 	if s.Else != nil {
 		P.separator = blank;
-		P.Token(0, token.ELSE);
+		P.Token(noloc, token.ELSE);
 		P.separator = blank;
 		P.Stat(s.Else);
 	}
@@ -883,7 +890,7 @@ func (P *Printer) DoIfStat(s *ast.IfStat) {
 
 
 func (P *Printer) DoForStat(s *ast.ForStat) {
-	P.Token(s.Pos, token.FOR);
+	P.Token(s.Loc, token.FOR);
 	P.ControlClause(true, s.Init, s.Cond, s.Post);
 	P.Block(s.Body, true);
 }
@@ -891,15 +898,15 @@ func (P *Printer) DoForStat(s *ast.ForStat) {
 
 func (P *Printer) DoCaseClause(s *ast.CaseClause) {
 	if s.Expr != nil {
-		P.Token(s.Pos, token.CASE);
+		P.Token(s.Loc, token.CASE);
 		P.separator = blank;
 		P.Expr(s.Expr);
 	} else {
-		P.Token(s.Pos, token.DEFAULT);
+		P.Token(s.Loc, token.DEFAULT);
 	}
 	// TODO: try to use P.Block instead
 	// P.Block(s.Body, true);
-	P.Token(s.Body.Pos, token.COLON);
+	P.Token(s.Body.Loc, token.COLON);
 	P.indentation++;
 	P.StatementList(s.Body.List);
 	P.indentation--;
@@ -908,21 +915,21 @@ func (P *Printer) DoCaseClause(s *ast.CaseClause) {
 
 
 func (P *Printer) DoSwitchStat(s *ast.SwitchStat) {
-	P.Token(s.Pos, token.SWITCH);
+	P.Token(s.Loc, token.SWITCH);
 	P.ControlClause(false, s.Init, s.Tag, nil);
 	P.Block(s.Body, false);
 }
 
 
 func (P *Printer) DoSelectStat(s *ast.SelectStat) {
-	P.Token(s.Pos, token.SELECT);
+	P.Token(s.Loc, token.SELECT);
 	P.separator = blank;
 	P.Block(s.Body, false);
 }
 
 
 func (P *Printer) DoControlFlowStat(s *ast.ControlFlowStat) {
-	P.Token(s.Pos, s.Tok);
+	P.Token(s.Loc, s.Tok);
 	if s.Label != nil {
 		P.separator = blank;
 		P.Expr(s.Label);
@@ -931,7 +938,7 @@ func (P *Printer) DoControlFlowStat(s *ast.ControlFlowStat) {
 
 
 func (P *Printer) DoEmptyStat(s *ast.EmptyStat) {
-	P.String(s.Pos, "");
+	P.String(s.Loc, "");
 }
 
 
@@ -939,23 +946,23 @@ func (P *Printer) DoEmptyStat(s *ast.EmptyStat) {
 // Declarations
 
 func (P *Printer) DoBadDecl(d *ast.BadDecl) {
-	P.String(d.Pos, "<BAD DECL>");
+	P.String(d.Loc, "<BAD DECL>");
 }
 
 
 func (P *Printer) DoImportDecl(d *ast.ImportDecl) {
-	if d.Pos > 0 {
-		P.Token(d.Pos, token.IMPORT);
+	if d.Loc.Pos > 0 {
+		P.Token(d.Loc, token.IMPORT);
 		P.separator = blank;
 	}
 	if d.Ident != nil {
 		P.Expr(d.Ident);
 	} else {
-		P.String(d.Path.Pos(), "");  // flush pending ';' separator/newlines
+		P.String(d.Path.Loc(), "");  // flush pending ';' separator/newlines
 	}
 	P.separator = tab;
 	if lit, is_lit := d.Path.(*ast.BasicLit); is_lit && lit.Tok == token.STRING {
-		P.HtmlPackageName(lit.Pos_, string(lit.Val));
+		P.HtmlPackageName(lit.Loc_, string(lit.Val));
 	} else {
 		// we should only reach here for strange imports
 		// import "foo" "bar"
@@ -966,8 +973,8 @@ func (P *Printer) DoImportDecl(d *ast.ImportDecl) {
 
 
 func (P *Printer) DoConstDecl(d *ast.ConstDecl) {
-	if d.Pos > 0 {
-		P.Token(d.Pos, token.CONST);
+	if d.Loc.Pos > 0 {
+		P.Token(d.Loc, token.CONST);
 		P.separator = blank;
 	}
 	P.Idents(d.Idents);
@@ -977,7 +984,7 @@ func (P *Printer) DoConstDecl(d *ast.ConstDecl) {
 	}
 	if d.Vals != nil {
 		P.separator = tab;
-		P.Token(0, token.ASSIGN);
+		P.Token(noloc, token.ASSIGN);
 		P.separator = blank;
 		P.Expr(d.Vals);
 	}
@@ -986,8 +993,8 @@ func (P *Printer) DoConstDecl(d *ast.ConstDecl) {
 
 
 func (P *Printer) DoTypeDecl(d *ast.TypeDecl) {
-	if d.Pos > 0 {
-		P.Token(d.Pos, token.TYPE);
+	if d.Loc.Pos > 0 {
+		P.Token(d.Loc, token.TYPE);
 		P.separator = blank;
 	}
 	P.Expr(d.Ident);
@@ -998,8 +1005,8 @@ func (P *Printer) DoTypeDecl(d *ast.TypeDecl) {
 
 
 func (P *Printer) DoVarDecl(d *ast.VarDecl) {
-	if d.Pos > 0 {
-		P.Token(d.Pos, token.VAR);
+	if d.Loc.Pos > 0 {
+		P.Token(d.Loc, token.VAR);
 		P.separator = blank;
 	}
 	P.Idents(d.Idents);
@@ -1010,7 +1017,7 @@ func (P *Printer) DoVarDecl(d *ast.VarDecl) {
 	}
 	if d.Vals != nil {
 		P.separator = tab;
-		P.Token(0, token.ASSIGN);
+		P.Token(noloc, token.ASSIGN);
 		P.separator = blank;
 		P.Expr(d.Vals);
 	}
@@ -1019,17 +1026,17 @@ func (P *Printer) DoVarDecl(d *ast.VarDecl) {
 
 
 func (P *Printer) funcDecl(d *ast.FuncDecl, with_body bool) {
-	P.Token(d.Pos, token.FUNC);
+	P.Token(d.Loc, token.FUNC);
 	P.separator = blank;
 	if recv := d.Recv; recv != nil {
 		// method: print receiver
-		P.Token(0, token.LPAREN);
+		P.Token(noloc, token.LPAREN);
 		if len(recv.Idents) > 0 {
 			P.Expr(recv.Idents[0]);
 			P.separator = blank;
 		}
 		P.Expr(recv.Typ);
-		P.Token(0, token.RPAREN);
+		P.Token(noloc, token.RPAREN);
 		P.separator = blank;
 	}
 	P.Expr(d.Ident);
@@ -1049,15 +1056,15 @@ func (P *Printer) DoFuncDecl(d *ast.FuncDecl) {
 
 func (P *Printer) DoDeclList(d *ast.DeclList) {
 	if !*def || d.Tok == token.IMPORT || d.Tok == token.VAR {
-		P.Token(d.Pos, d.Tok);
+		P.Token(d.Loc, d.Tok);
 	} else {
-		P.String(d.Pos, "def");
+		P.String(d.Loc, "def");
 	}
 	P.separator = blank;
 
 	// group of parenthesized declarations
 	P.state = opening_scope;
-	P.Token(0, token.LPAREN);
+	P.Token(noloc, token.LPAREN);
 	if len(d.List) > 0 {
 		P.newlines = 1;
 		for i := 0; i < len(d.List); i++ {
@@ -1099,7 +1106,7 @@ func (P *Printer) Interface(p *ast.Program) {
 				/*
 				P.Printf("<p><code>");
 				P.funcDecl(d, false);
-				P.String(0, "");
+				P.String(noloc, "");
 				P.Printf("</code></p>");
 				*/
 			}
@@ -1112,7 +1119,7 @@ func (P *Printer) Interface(p *ast.Program) {
 // Program
 
 func (P *Printer) Program(p *ast.Program) {
-	P.Token(p.Pos, token.PACKAGE);
+	P.Token(p.Loc, token.PACKAGE);
 	P.separator = blank;
 	P.Expr(p.Ident);
 	P.newlines = 1;
@@ -1160,7 +1167,7 @@ func Print(writer io.Write, html bool, prog *ast.Program) {
 		P.Program(prog);
 	}
 
-	P.String(0, "");  // flush pending separator/newlines
+	P.String(noloc, "");  // flush pending separator/newlines
 	err := text.Flush();
 	if err != nil {
 		panic("print error - exiting");
diff --git a/usr/gri/pretty/typechecker.go b/usr/gri/pretty/typechecker.go
index 890bbe0405..8cc0d5975f 100644
--- a/usr/gri/pretty/typechecker.go
+++ b/usr/gri/pretty/typechecker.go
@@ -6,22 +6,18 @@ package TypeChecker
 
 import (
 	"token";
-	AST "ast";
+	"scanner";
+	"ast";
 )
 
 
-type ErrorHandler interface {
-	Error(pos int, msg string);
-}
-
-
 type state struct {
 	// setup
-	err ErrorHandler;
+	err scanner.ErrorHandler;
 }
 
 
-func (s *state) Init(err ErrorHandler) {
+func (s *state) Init(err scanner.ErrorHandler) {
 	s.err = err;
 }
 
@@ -46,8 +42,8 @@ func assert(pred bool) {
 }
 
 
-func (s *state) Error(pos int, msg string) {
-	s.err.Error(pos, msg);
+func (s *state) Error(loc scanner.Location, msg string) {
+	s.err.Error(loc, msg);
 }
 
 
@@ -81,7 +77,7 @@ func (s *state) CheckDeclaration(d *AST.Decl) {
 */
 
 
-func (s *state) CheckProgram(p *AST.Program) {
+func (s *state) CheckProgram(p *ast.Program) {
 	for i := 0; i < len(p.Decls); i++ {
 		//s.CheckDeclaration(p.Decls[i].(*AST.Decl));
 	}
@@ -90,7 +86,7 @@ func (s *state) CheckProgram(p *AST.Program) {
 
 // ----------------------------------------------------------------------------
 
-func CheckProgram(err ErrorHandler, p *AST.Program) {
+func CheckProgram(err scanner.ErrorHandler, p *ast.Program) {
 	var s state;
 	s.Init(err);
 	s.CheckProgram(p);