diff --git a/compiler/fn.v b/compiler/fn.v
index 2134094d2b..50618bc3da 100644
--- a/compiler/fn.v
+++ b/compiler/fn.v
@@ -13,6 +13,7 @@ const (
 struct Fn {
 	// addr int
 mut:
+	name          string
 	pkg           string
 	local_vars    []Var
 	var_idx       int
@@ -22,7 +23,6 @@ mut:
 	// idx           int
 	scope_level   int
 	typ           string // return type
-	name          string
 	is_c          bool
 	receiver_typ  string
 	is_public    bool
diff --git a/compiler/main.v b/compiler/main.v
index 7fdec70056..e9d647da62 100644
--- a/compiler/main.v
+++ b/compiler/main.v
@@ -356,8 +356,7 @@ string _STR_TMP(const char *fmt, ...) {
 		// Generate `main` which calls every single test function
 		else if v.pref.is_test {
 			cgen.genln('int main() { init_consts();')
-			for entry in v.table.fns.entries { 
-				f := v.table.fns[entry.key] 
+			for key, f in v.table.fns { 
 				if f.name.starts_with('test_') {
 					cgen.genln('$f.name();')
 				}
@@ -680,7 +679,7 @@ fn (v &V) v_files_from_dir(dir string) []string {
 		if file.ends_with('_mac.v') && v.os != .mac { 
 			lin_file := file.replace('_mac.v', '_lin.v')
 			// println('lin_file="$lin_file"')
-			// If there are both _mav.v and _lin.v, don't use _mav.v
+			// If there are both _mac.v and _lin.v, don't use _mav.v
 			if os.file_exists('$dir/$lin_file') {
 				continue
 			}
@@ -1035,7 +1034,7 @@ fn run_repl() []string {
 			mut temp_line := line
 			mut temp_flag := false
 			if !(line.contains(' ') || line.contains(':') || line.contains('=') || line.contains(',') ){
-				temp_line = 'println('+line+')'
+				temp_line = 'println($line)'
 				temp_flag = true
 			}
 			temp_source_code := lines.join('\n') + '\n' + temp_line
@@ -1064,7 +1063,6 @@ fn run_repl() []string {
 	return lines
 }
 
-// This definitely needs to be better :)
 const (
 	HelpText = '
 Usage: v [options] [file | directory]
@@ -1077,8 +1075,7 @@ Options:
   -prod             Build an optimized executable.
   -o <file>         Place output into <file>.
   -obf              Obfuscate the resulting binary.
-  run               Build and execute a V program.
-                    You can add arguments after file name.
+  run               Build and execute a V program. You can add arguments after file name.
 
 Files:
   <file>_test.v     Test file.
diff --git a/compiler/parser.v b/compiler/parser.v
index 345b43348f..1de611014f 100644
--- a/compiler/parser.v
+++ b/compiler/parser.v
@@ -1200,7 +1200,7 @@ fn (p mut Parser) var_decl() {
 fn (p mut Parser) bool_expression() string {
 	tok := p.tok
 	typ := p.bterm()
-	for p.tok == .and || p.tok == .ortok {
+	for p.tok == .and || p.tok == .logical_or {
 		p.gen(' ${p.tok.str()} ')
 		p.check_space(p.tok) 
 		p.check_types(p.bterm(), typ)
@@ -2916,10 +2916,21 @@ fn (p mut Parser) for_st() {
 				is_mut: true
 			}
 			p.register_var(i_var)
+			p.genln('array_string keys_$tmp = map_keys(& $tmp ); ') 
+			p.genln('for (int l = 0; l < keys_$tmp .len; l++) {') 
+			p.genln('  string $i = ((string*)keys_$tmp .data)[l];') 
+			//p.genln('  string $i = *(string*) ( array__get(keys_$tmp, l) );') 
+			def := type_default(var_typ) 
+			// TODO don't call map_get() for each key, fetch values while traversing
+			// the tree (replace `map_keys()` above with `map_key_vals()`) 
+			p.genln('$var_typ $val = $def; map_get($tmp, $i, & $val);') 
+			
+			/* 
 			p.genln('for (int l = 0; l < $tmp . entries.len; l++) {') 
 			p.genln('Entry entry = *((Entry*) (array__get($tmp .entries, l)));') 
 			p.genln('string $i = entry.key;') 
 			p.genln('$var_typ $val; map_get($tmp, $i, & $val);') 
+			*/ 
 		} 
 	}
 	// `for val in vals`
diff --git a/compiler/scanner.v b/compiler/scanner.v
index b9255109a9..d583d18000 100644
--- a/compiler/scanner.v
+++ b/compiler/scanner.v
@@ -344,7 +344,7 @@ fn (s mut Scanner) scan() ScanRes {
 	case `|`:
 		if nextc == `|` {
 			s.pos++
-			return scan_res(.ortok, '')
+			return scan_res(.logical_or, '')
 		}
 		if nextc == `=` {
 			s.pos++
diff --git a/compiler/table.v b/compiler/table.v
index 9ec7a1a255..2f35bfa8ec 100644
--- a/compiler/table.v
+++ b/compiler/table.v
@@ -565,8 +565,7 @@ fn (t &Table) is_interface(name string) bool {
 
 // Do we have fn main()?
 fn (t &Table) main_exists() bool {
-	for entry in t.fns.entries { 
-		f := t.fns[entry.key] 
+	for _, f in t.fns { 
 		if f.name == 'main' {
 			return true
 		}
@@ -696,11 +695,11 @@ fn (fit mut FileImportTable) register_import(mod string) {
 }
 
 fn (fit mut FileImportTable) register_alias(alias string, mod string) {
-	if !fit.imports.exists(alias) {
-		fit.imports[alias] = mod
-	} else {
-		panic('Cannot import $mod as $alias: import name $alias already in use in "${fit.file_path}".')
-	}
+	if fit.imports.exists(alias) {
+		panic('cannot import $mod as $alias: import name $alias already in use in "${fit.file_path}".')
+		return 
+	} 
+	fit.imports[alias] = mod
 }
 
 fn (fit &FileImportTable) known_alias(alias string) bool {
@@ -708,10 +707,10 @@ fn (fit &FileImportTable) known_alias(alias string) bool {
 }
 
 fn (fit &FileImportTable) is_aliased(mod string) bool {
-	for i in fit.imports.keys() {
-		if fit.imports[i] == mod {
-			return true
-		}
+	for _, val in fit.imports { 
+		if val == mod {
+			return true 
+		} 
 	}
 	return false
 }
diff --git a/compiler/token.v b/compiler/token.v
index 7802c63a97..c1c9e56400 100644
--- a/compiler/token.v
+++ b/compiler/token.v
@@ -20,7 +20,7 @@ enum Token {
 	inc
 	dec
 	and
-	ortok
+	logical_or 
 	not 
 	bit_not
 	question
@@ -67,51 +67,51 @@ enum Token {
 	dotdot
 	// keywords
 	keyword_beg
-	key_module
-	key_struct
-	key_if 
-	key_else
-	key_return
-	key_go
-	key_const
-	key_import_const 
-	key_mut
-	typ
-	key_enum
-	key_for
-	key_switch 
-	MATCH
-	key_case
-	func
-	key_true
-	key_false
-	key_continue
-	key_break
-	key_embed
-	key_import
-	//typeof 
-	key_default 
+	key_as
 	key_assert
-	key_sizeof
-	key_in 
 	key_atomic
-	key_interface 
-	key_orelse
+	key_break
+	key_case
+	key_const
+	key_continue
+	key_default 
+	key_else
+	key_embed
+	key_enum
+	key_false
+	key_for
+	func
 	key_global
+	key_go
+	key_goto 
+	key_if 
+	key_import
+	key_import_const 
+	key_in 
+	key_interface 
+	MATCH
+	key_module
+	key_mut
+	key_return
+	key_sizeof
+	key_struct
+	key_switch 
+	key_true
+	typ
+	//typeof 
+	key_orelse
 	key_union
 	key_pub 
-	key_goto 
 	key_static
-	key_as
 	keyword_end
 }
 
 // build_keys genereates a map with keywords' string values:
 // Keywords['return'] == .key_return
-fn build_keys() map_int {
+fn build_keys() map[string]int {
 	mut res := map[string]int{}
 	for t := int(Token.keyword_beg) + 1; t < int(Token.keyword_end); t++ {
-		key := TOKENSTR[t]
+		key := TokenStr[t]
 		res[key] = int(t)
 	}
 	return res
@@ -140,7 +140,7 @@ fn build_token_str() []string {
 	s[Token.inc] = '++'
 	s[Token.dec] = '--'
 	s[Token.and] = '&&'
-	s[Token.ortok] = '||'
+	s[Token.logical_or] = '||'
 	s[Token.not] = '!'
 	s[Token.dot] = '.'
 	s[Token.dotdot] = '..'
@@ -218,7 +218,7 @@ fn build_token_str() []string {
 
 const (
 	NrTokens = 140
-	TOKENSTR = build_token_str()
+	TokenStr = build_token_str()
 	KEYWORDS = build_keys()
 )
 
@@ -232,11 +232,13 @@ fn is_key(key string) bool {
 }
 
 fn (t Token) str() string {
-	return TOKENSTR[int(t)]
+	return TokenStr[int(t)]
 }
 
 fn (t Token) is_decl() bool {
-	// TODO return t in [.func ,.typ, .key_const,  .key_import_.key_const ,AT ,.eof]
+	// TODO i
+	//return t in [.key_enum, .key_interface, .func, .typ, .key_const,  
+		//.key_import_const, .key_struct, .key_pub, .eof]
 	return t == .key_enum || t == .key_interface || t == .func || 
 	t == .key_struct || t == .typ ||
 	t == .key_const || t == .key_import_const || t == .key_pub || t == .eof
diff --git a/vlib/builtin/map.v b/vlib/builtin/map.v
index af89fb91d1..bbc55a1916 100644
--- a/vlib/builtin/map.v
+++ b/vlib/builtin/map.v
@@ -5,60 +5,116 @@
 module builtin
 
 struct map {
-	// cap          int
-	// keys         []string
-	// table        byteptr
-	// keys_table   *string
-	// table *Entry
 	element_size int
-	// collisions   []Entry
-pub:
-	entries      []Entry
-	is_sorted    bool
+	root      *Node 
+	_keys []string // used by `keys()` TODO remove this from map struct, 
+	key_i int      // store in a separate var 
+pub: 
+	size int 
 }
 
-struct Entry {
-pub:
+struct Node {
+	left *Node
+	right *Node 
 	key string
 	val voidptr
-	// linked list for collisions
-	// next *Entry
 }
 
 fn new_map(cap, elm_size int) map {
 	res := map {
-		// len: len,
 		element_size: elm_size
-		// entries:
-		// keys: []string
+		root: 0 
 	}
 	return res
 }
 
-fn (m &map) new_entry(key string, val voidptr) Entry {
-	new_e := Entry {
+fn new_node(key string, val voidptr, element_size int) *Node {
+	new_e := &Node {
 		key: key
-		val: malloc(m.element_size)
-		// next: 0
+		val: malloc(element_size)
+		left: 0
+		right: 0 
 	}
-	C.memcpy(new_e.val, val, m.element_size)
+	C.memcpy(new_e.val, val, element_size)
 	return new_e
 }
 
+fn (m mut map) insert(n mut Node, key string, val voidptr) {
+	if n.key == key {
+		C.memcpy(n.val, val, m.element_size)
+		return 
+	} 
+	if n.key > key {
+		if isnil(n.left) {
+			n.left = new_node(key, val, m.element_size) 
+			m.size++ 
+		}  else { 
+			m.insert(mut n.left, key, val) 
+		} 
+		return 
+	} 
+	if isnil(n.right) {
+		n.right = new_node(key, val, m.element_size)  
+		m.size++ 
+	}  else { 
+		m.insert(mut n.right, key, val) 
+	} 
+} 
+
+fn (n & Node) find(key string, out voidptr, element_size int) bool{ 
+	if n.key == key {
+		C.memcpy(out, n.val, element_size)
+		return true 
+	} 
+	else if n.key > key {
+		if isnil(n.left) {
+			return false 
+		}  else { 
+			return n.left.find(key, out, element_size) 
+		} 
+	} 
+	else {
+		if isnil(n.right) {
+			return false 
+		}  else { 
+			return n.right.find(key, out, element_size) 
+		} 
+	} 
+	return false 
+} 
+
+// same as `find`, but doesn't return a value. Used by `exists` 
+fn (n & Node) find2(key string, element_size int) bool{ 
+	if n.key == key {
+		return true 
+	} 
+	else if n.key > key {
+		if isnil(n.left) {
+			return false 
+		}  else { 
+			return n.left.find2(key, element_size) 
+		} 
+	} 
+	else {
+		if isnil(n.right) {
+			return false 
+		}  else { 
+			return n.right.find2(key, element_size) 
+		} 
+	} 
+	return false 
+} 
+
 fn (m mut map) _set(key string, val voidptr) {
-	e := m.new_entry(key, val)
-	for i := 0; i < m.entries.len; i++ {
-		entry := m.entries[i]
-		if entry.key == key {
-			// e := Entry2{key: key, val: val}
-			m.entries[i] = e
-			return
-		}
-	}
-	m.entries << e// m.new_entry(key, val)
-	m.is_sorted = false
+	if isnil(m.root) {
+		m.root = new_node(key, val, m.element_size) 
+		m.size++ 
+		return 
+	} 
+	m.insert(mut m.root, key, val) 
 }
 
+/* 
 fn (m map) bs(query string, start, end int, out voidptr) {
 	// println('bs "$query" $start -> $end')
 	mid := start + ((end - start) / 2)
@@ -83,63 +139,46 @@ fn (m map) bs(query string, start, end int, out voidptr) {
 	}
 	m.bs(query, mid, end, out)
 }
+*/ 
 
-fn compare_map(a, b *Entry) int {
-	if a.key < b.key {
-		return -1
-	}
-	if a.key > b.key {
-		return 1
-	}
-	return 0
-}
+fn (m mut map) preorder_keys(node &Node) { 
+	m._keys[m.key_i] = node.key 
+	m.key_i++ 
+	if !isnil(node.left) { 
+		m.preorder_keys(node.left) 
+	} 
+	if !isnil(node.right) { 
+		m.preorder_keys(node.right) 
+	} 
+} 
 
-pub fn (m mut map) sort() {
-	m.entries.sort_with_compare(compare_map)
-	m.is_sorted = true
-}
-
-pub fn (m map) keys() []string {
-	mut keys := []string{}
-	for i := 0; i < m.entries.len; i++ {
-		entry := m.entries[i]
-		keys << entry.key
-	}
-	return keys
+pub fn (m mut map) keys() []string {
+	m._keys = [''; m.size] 
+	m.key_i = 0 
+	if isnil(m.root) {
+		return m._keys
+	} 
+	m.preorder_keys(m.root) 
+	return m._keys
 }
 
 fn (m map) get(key string, out voidptr) bool {
-	if m.is_sorted {
-		// println('\n\nget "$key" sorted')
-		m.bs(key, 0, m.entries.len, out)
-		return true
-	}
-	for i := 0; i < m.entries.len; i++ {
-		entry := m.entries[i]
-		if entry.key == key {
-			C.memcpy(out, entry.val, m.element_size)
-			return true
-		}
-	}
-	return false
+	if isnil(m.root) {
+		return false 
+	} 
+	return m.root.find(key, out, m.element_size) 
 }
 
 pub fn (m map) exists(key string) bool {
-	for i := 0; i < m.entries.len; i++ {
-		entry := m.entries[i]
-		if entry.key == key {
-			return true
-		}
-	}
-	return false
+	return !isnil(m.root) && m.root.find2(key, m.element_size) 
 }
 
 pub fn (m map) print() {
 	println('<<<<<<<<')
-	for i := 0; i < m.entries.len; i++ {
+	//for i := 0; i < m.entries.len; i++ {
 		// entry := m.entries[i]
 		// println('$entry.key => $entry.val')
-	}
+	//}
 	/*
 	for i := 0; i < m.cap * m.element_size; i++ {
 		b := m.table[i]
@@ -158,15 +197,15 @@ pub fn (m map) free() {
 
 pub fn (m map_string) str() string {
 	// return 'not impl'
-	if m.entries.len == 0 {
+	if m.size == 0 {
 		return '{}'
 	}
 	// TODO use bytes buffer
 	mut s := '{\n'
-	for entry in m.entries {
-		val := m[entry.key]
-		s += '  "$entry.key" => "$val"\n'
-	}
+	//for entry in m.entries {
+		//val := m[entry.key]
+		//s += '  "$entry.key" => "$val"\n'
+	//}
 	s += '}'
 	return s
 }
diff --git a/vlib/builtin/map_test.v b/vlib/builtin/map_test.v
index 7758f71e3e..4f41cdcbeb 100644
--- a/vlib/builtin/map_test.v
+++ b/vlib/builtin/map_test.v
@@ -1,3 +1,5 @@
+import time 
+ 
 struct User {
 	name string 
 } 
@@ -13,13 +15,32 @@ fn (a mut A) set(key string, val int) {
 
 fn test_map() {
 	mut m := map[string]int{}
+	assert m.size == 0 
 	m['hi'] = 80
+	m['hello'] = 101 
 	assert m['hi'] == 80
+	assert m['hello'] == 101 
+	assert m.size == 2 
+	mut sum := 0
+	mut key_sum := '' 
+	// Test `for in` 
+	for key, val in m {
+		sum += val 
+		key_sum += key 
+	} 
+	assert sum == 80 + 101 
+	assert key_sum == 'hihello' 
+	// Test `.keys()` 
+	keys := m.keys() 
+	assert keys.len == 2 
+	assert keys[0] == 'hi'
+	assert keys[1] == 'hello' 
 	//// 
 	mut users := map[string]User{} 
 	users['1'] = User{'Peter'} 
 	peter := users['1']
 	assert  peter.name == 'Peter' 
+	println(peter.name) 
 
 	mut a := A{
 		m: map[string]int{} 
@@ -33,3 +54,22 @@ fn test_map() {
 	assert a.m['one'] == 1
 	assert a.m['two'] == 2
 }
+
+fn test_string_map() {
+	//m := map[string]Fn
+} 
+
+fn test_large_map() { 
+	//ticks := time.ticks() 
+	mut nums := map[string]int{} 
+	N := 30 * 1000
+	for i := 0; i < N; i++ {
+	        key := i.str()
+	        nums[key] = i
+	}
+	assert nums['1'] == 1 
+	assert nums['999'] == 999 
+	assert nums['1000000'] == 0 
+	//println(time.ticks() - ticks) 
+} 
+