diff --git a/examples/selfhost/tokenizer.zr b/examples/selfhost/tokenizer.zr
new file mode 100644
index 0000000..cb76baf
--- /dev/null
+++ b/examples/selfhost/tokenizer.zr
@@ -0,0 +1,408 @@
+const TT_LEFT_PAREN    = 1
+const TT_RIGHT_PAREN   = 2
+const TT_LEFT_BRACKET  = 3
+const TT_RIGHT_BRACKET = 4
+const TT_COMMA         = 5
+const TT_PLUS          = 6
+const TT_PLUS_EQUAL    = 7
+const TT_MINUS         = 8
+const TT_MINUS_EQUAL   = 9
+const TT_STAR          = 10
+const TT_SLASH         = 11
+const TT_MOD           = 12
+const TT_XOR           = 13
+const TT_BANG          = 14
+const TT_COLON         = 15
+const TT_BIT_AND       = 16
+const TT_BIT_OR        = 17
+const TT_LOGICAL_AND   = 18
+const TT_LOGICAL_OR    = 19
+const TT_DOUBLE_DOT    = 20
+const TT_SHIFT_LEFT    = 21
+const TT_SHIFT_RIGHT   = 22
+const TT_ARROW         = 23
+const TT_TILDE         = 24
+
+const TT_EQUAL         = 25
+const TT_DOUBLE_EQUAL  = 26
+const TT_NOT_EQUAL     = 27
+const TT_GREATER       = 28
+const TT_GREATER_EQUAL = 29
+const TT_LESS          = 30
+const TT_LESS_EQUAL    = 31
+
+const TT_IDENTIFIER     = 32
+const TT_STRING_LITERAL = 33
+const TT_CHAR_LITERAL   = 34
+const TT_INT_LITERAL    = 35
+const TT_TRUE           = 36
+const TT_FALSE          = 37
+
+const TT_KW_CONST    = 38
+const TT_KW_IF       = 39
+const TT_KW_ELSE     = 40
+const TT_KW_WHILE    = 41
+const TT_KW_FOR      = 42
+const TT_KW_IN       = 43
+const TT_KW_FUNC     = 44
+const TT_KW_RETURN   = 45
+const TT_KW_BREAK    = 46
+const TT_KW_CONTINUE = 47
+const TT_KW_EXTERN   = 48
+const TT_KW_EXPORT   = 49
+const TT_KW_STRUCT   = 50
+const TT_KW_NEW      = 51
+const TT_KW_AS       = 52
+
+const TT_INDENT = 53
+const TT_DEDENT = 54
+const TT_EOF    = 55
+
+struct Token
+    token_type: i64
+    lexeme: str
+    loc_filename: str
+    loc_line: i64
+    loc_column: i64
+
+struct Tokenizer
+    source: str
+    source_len: i64
+    tokens: Array
+    indent_stack: Array
+    current_indent: i64
+    start: i64
+    current: i64
+    loc_filename: str
+    loc_line: i64
+    loc_column: i64
+
+func Tokenizer.init[t: Tokenizer, filename: str, source: str] : void
+    t->source = source
+    t->source_len = str.len(source)
+    t->tokens = []
+    t->indent_stack = [0]
+    t->loc_filename = filename
+    t->loc_line = 1
+    t->loc_column = 1
+
+func Tokenizer.tokenize[t: Tokenizer] : Array
+    while !t->eof()
+        t->start = t->current
+        t->scan_token()
+
+    t->add_token(TT_EOF, "")
+    return t->tokens
+
+func Tokenizer.scan_token[t: Tokenizer] : void
+    c := t->advance()
+    if c == '('
+        t->add_token(TT_LEFT_PAREN, "(")
+    else if c == ')'
+        t->add_token(TT_RIGHT_PAREN, ")")
+    else if c == '['
+        t->add_token(TT_LEFT_BRACKET, "[")
+    else if c == ']'
+        t->add_token(TT_RIGHT_BRACKET, "]")
+    else if c == '+'
+        if t->match_char('=')
+            t->add_token(TT_PLUS_EQUAL, "+=")
+        else
+            t->add_token(TT_PLUS, "+")
+    else if c == '*'
+        t->add_token(TT_STAR, "*")
+    else if c == ','
+        t->add_token(TT_COMMA, ",")
+    else if c == '%'
+        t->add_token(TT_MOD, "%")
+    else if c == '^'
+        t->add_token(TT_XOR, "^")
+    else if c == ':'
+        t->add_token(TT_COLON, ":")
+    else if c == '~'
+        t->add_token(TT_TILDE, "~")
+    else if c == '-'
+        if t->match_char('=')
+            t->add_token(TT_MINUS_EQUAL, "-=")
+        else if t->match_char('>')
+            t->add_token(TT_ARROW, "->")
+        else
+            t->add_token(TT_MINUS, "-")
+    else if c == '.'
+        if t->match_char('.')
+            t->add_token(TT_DOUBLE_DOT, "..")
+        else
+            t->error("expected '.' after '.'")
+    else if c == '/'
+        if t->match_char('/')
+            while !t->eof() && t->peek() != '\n'
+                t->advance()
+        else
+            t->add_token(TT_SLASH, "/")
+    else if c == '&'
+        if t->match_char('&')
+            t->add_token(TT_LOGICAL_AND, "&&")
+        else
+            t->add_token(TT_BIT_AND, "&")
+    else if c == '|'
+        if t->match_char('|')
+            t->add_token(TT_LOGICAL_OR, "||")
+        else
+            t->add_token(TT_BIT_OR, "|")
+    else if c == '!'
+        if t->match_char('=')
+            t->add_token(TT_NOT_EQUAL, "!=")
+        else
+            t->add_token(TT_BANG, "!")
+    else if c == '='
+        if t->match_char('=')
+            t->add_token(TT_DOUBLE_EQUAL, "==")
+        else
+            t->add_token(TT_EQUAL, "=")
+    else if c == '>'
+        if t->match_char('>')
+            t->add_token(TT_SHIFT_RIGHT, ">>")
+        else if t->match_char('=')
+            t->add_token(TT_GREATER_EQUAL, ">=")
+        else
+            t->add_token(TT_GREATER, ">")
+    else if c == '<'
+        if t->match_char('<')
+            t->add_token(TT_SHIFT_LEFT, "<<")
+        else if t->match_char('=')
+            t->add_token(TT_LESS_EQUAL, "<=")
+        else
+            t->add_token(TT_LESS, "<")
+    else if c == '\''
+        if t->eof()
+            t->error("unterminated char literal")
+
+        t->match_char('\\')
+        t->advance()
+
+        if !t->match_char('\'')
+            t->error("expected ' after char literal")
+
+        lexeme := t->source->substr(t->start, t->current - t->start)
+        t->add_token(TT_CHAR_LITERAL, lexeme)
+    else if c == '"'
+        start_filename := t->loc_filename
+        start_line := t->loc_line
+        start_column := t->loc_column
+
+        while !t->eof()
+            if t->peek() == '\\'
+                t->advance()
+            else if t->peek() == '"'
+                break
+            else if t->peek() == '\n'
+                t->loc_line += 1
+                t->loc_column = 0
+
+            t->advance()
+
+        if t->eof()
+            t->loc_filename = start_filename
+            t->loc_line = start_line
+            t->loc_column = start_column
+            t->error("unterminated string")
+
+        t->advance()
+        lexeme := t->source->substr(t->start, t->current - t->start)
+        t->add_token(TT_STRING_LITERAL, lexeme)
+    else if c == ' ' || c == '\r'
+        // ignore
+    else if c == '\n'
+        t->loc_line += 1
+        t->loc_column = 1
+        t->handle_indentation()
+    else if c >= '0' && c <= '9'
+        t->scan_number()
+    else if (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_'
+        t->scan_identifier()
+    else
+        t->error("unexpected character")
+
+func Tokenizer.handle_indentation[t: Tokenizer] : void
+    if t->peek() == '\n'
+        return 0
+    
+    new_indent := t->count_indentation()
+
+    if new_indent > t->current_indent
+        t->indent_stack->push(new_indent)
+        t->add_token(TT_INDENT, "")
+    else if new_indent < t->current_indent
+        while t->indent_stack->size > 0 && t->indent_stack->last() > new_indent
+            t->indent_stack->pop()
+            t->add_token(TT_DEDENT, "")
+        if t->indent_stack->size == 0 || t->indent_stack->last() != new_indent
+            t->error("invalid indentation")
+    
+    t->current_indent = new_indent
+
+func Tokenizer.count_indentation[t: Tokenizer] : i64
+    count := 0
+    while t->peek() == ' '
+        count += 1
+        t->advance()
+    return count
+
+func Tokenizer.scan_number[t: Tokenizer] : void
+    if t->match_char('x')
+        while t->peek()->is_hex_digit()
+            t->advance()
+    else if t->match_char('o')
+        while '0' <= t->peek() && t->peek() <= '7'
+            t->advance()
+    else
+        while t->peek()->is_digit()
+            t->advance()
+    
+    lexeme := t->source->substr(t->start, t->current - t->start)
+    t->add_token(TT_INT_LITERAL, lexeme)
+
+func str.match_at[s: str, start: i64, keyword: str] : bool
+    i := 0
+    while keyword[i] != 0
+        if s[start + i] != keyword[i]
+            return false
+        i += 1
+    return true
+
+func Tokenizer.scan_identifier[t: Tokenizer] : void
+    while t->peek()->is_alphanumeric() || t->peek() == '_' || t->peek() == '.'
+        t->advance()
+
+    len := t->current - t->start
+
+    if len == 5 && t->source->match_at(t->start, "const")
+        t->add_token(TT_KW_CONST, "const")
+    else if len == 2 && t->source->match_at(t->start, "if")
+        t->add_token(TT_KW_IF, "if")
+    else if len == 4 && t->source->match_at(t->start, "else")
+        t->add_token(TT_KW_ELSE, "else")
+    else if len == 5 && t->source->match_at(t->start, "while")
+        t->add_token(TT_KW_WHILE, "while")
+    else if len == 3 && t->source->match_at(t->start, "for")
+        t->add_token(TT_KW_FOR, "for")
+    else if len == 2 && t->source->match_at(t->start, "in")
+        t->add_token(TT_KW_IN, "in")
+    else if len == 4 && t->source->match_at(t->start, "func")
+        t->add_token(TT_KW_FUNC, "func")
+    else if len == 6 && t->source->match_at(t->start, "return")
+        t->add_token(TT_KW_RETURN, "return")
+    else if len == 5 && t->source->match_at(t->start, "break")
+        t->add_token(TT_KW_BREAK, "break")
+    else if len == 8 && t->source->match_at(t->start, "continue")
+        t->add_token(TT_KW_CONTINUE, "continue")
+    else if len == 6 && t->source->match_at(t->start, "extern")
+        t->add_token(TT_KW_EXTERN, "extern")
+    else if len == 6 && t->source->match_at(t->start, "export")
+        t->add_token(TT_KW_EXPORT, "export")
+    else if len == 6 && t->source->match_at(t->start, "struct")
+        t->add_token(TT_KW_STRUCT, "struct")
+    else if len == 3 && t->source->match_at(t->start, "new")
+        t->add_token(TT_KW_NEW, "new")
+    else if len == 2 && t->source->match_at(t->start, "as")
+        t->add_token(TT_KW_AS, "as")
+    else if len == 4 && t->source->match_at(t->start, "true")
+        t->add_token(TT_TRUE, "true")
+    else if len == 5 && t->source->match_at(t->start, "false")
+        t->add_token(TT_FALSE, "false")
+    else
+        lexeme := t->source->substr(t->start, len)
+        t->add_token(TT_IDENTIFIER, lexeme)
+
+func Tokenizer.match_char[t: Tokenizer, expected: u8] : bool
+    if t->eof() || t->peek() != expected
+        return false
+    t->current += 1
+    t->loc_column += 1
+    return true
+
+func Tokenizer.add_token[t: Tokenizer, token_type: i64, lexeme: str] : void
+    if token_type == TT_STRING_LITERAL || token_type == TT_CHAR_LITERAL
+        lexeme = t->unescape(lexeme)
+
+    token := new* Token
+    token->token_type = token_type
+    token->lexeme = lexeme
+    token->loc_filename = t->loc_filename
+    token->loc_line = t->loc_line
+    token->loc_column = t->loc_column
+    t->tokens->push(token)
+
+func Tokenizer.unescape[t: Tokenizer, s: str] : str
+    b := new str.Builder
+    i := 0
+    len := s->len()
+    while i < len
+        if s[i] == '\\'
+            i += 1
+            if i >= len
+                t->error("unexpected end of escape sequence")
+
+            if s[i] == 'n'
+                b->append_char('\n')
+            else if s[i] == 'r'
+                b->append_char('\r')
+            else if s[i] == 't'
+                b->append_char('\t')
+            else if s[i] == '0'
+                b->append_char('\0')
+            else if s[i] == '\\'
+                b->append_char('\\')
+            else if s[i] == '\''
+                b->append_char('\'')
+            else if s[i] == '"'
+                b->append_char('"')
+            else
+                t->error("unknown escape sequence")
+        else
+            b->append_char(s[i])
+        i += 1
+
+    result := b->build()
+    b->destroy()
+    return result
+
+func Tokenizer.advance[t: Tokenizer] : u8
+    c := t->source[t->current]
+    t->current += 1
+    t->loc_column += 1
+    return c
+
+func Tokenizer.peek[t: Tokenizer] : u8
+    if t->eof()
+        return '\0'
+    return t->source[t->current]
+
+func Tokenizer.eof[t: Tokenizer] : bool
+    return t->current >= t->source_len
+
+func Tokenizer.error[t: Tokenizer, msg: str] : void
+    io.print(t->loc_filename)
+    io.print(":")
+    io.print_i64(t->loc_line)
+    io.print(":")
+    io.print_i64(t->loc_column)
+    io.print(" ERROR: ")
+    io.println(msg)
+    os.exit(1)
+
+func main[argc: i64, argv: ptr] : i64
+    path := mem.read64(argv + 8) as str
+    ~source, ok := io.read_text_file(path)
+    if !ok
+        panic("file not found")
+    
+    filename := os.basename(path)
+
+    tokenizer := new Tokenizer
+    tokenizer->init(filename, source)
+
+    tokens := tokenizer->tokenize()
+    for i in 0..tokens->size
+        t := tokens->nth(i) as Token
+        io.printf("Token(token_type=%d, lexeme=\"%s\", loc=\"%s:%d:%d\")\n", t->token_type, t->lexeme, t->loc_filename, t->loc_line, t->loc_column)
diff --git a/src/std/std.zr b/src/std/std.zr
index 286b8a7..78aee04 100644
--- a/src/std/std.zr
+++ b/src/std/std.zr
@@ -849,7 +849,7 @@ func Array.new_preallocated_and_zeroed[size: i64] : Array
 
 func Array.nth[xs: Array, n: i64] : any
     if n < 0 || n >= xs->size
-        panic("array.nth out of bounds")
+        panic("Array.nth out of bounds")
     return mem.read64(xs->data + n * 8)
 
 func Array.set[xs: Array, n: i64, x: any] : void
@@ -882,14 +882,19 @@ func Array.free_with_items[xs: Array] : void
 
 func Array.pop[xs: Array] : any
     if xs->size == 0
-        panic("array.pop on empty array")
-    x : any = xs->nth(xs->size - 1)
+        panic("Array.pop on empty array")
+    x : any = Array.last(xs)
     xs->size = xs->size - 1
     return x
 
+func Array.last[xs: Array] : any
+    if xs->size == 0
+        panic("Array.last on empty array")
+    return xs->nth(xs->size - 1)
+
 func Array.slice[xs: Array, start: i64, length: i64] : Array
     if start < 0 || length < 0 || start + length > xs->size
-        panic("array.slice out of bounds")
+        panic("Array.slice out of bounds")
 
     new_array := Array.new_preallocated_and_zeroed(length)
     mem.copy(xs->data + start * 8, new_array->data, length * 8)