diff --git a/file/error.go b/file/error.go
index e7f72e4..6a0d502 100644
--- a/file/error.go
+++ b/file/error.go
@@ -58,7 +58,8 @@ func (err Error) Error () (formattedMessage string) {
 
 		// print an arrow with a tail spanning the width of the mistake
 		columnCountdown := err.Location.column
-		for columnCountdown > 0 {
+		for columnCountdown > 1 {
+			// TODO: for tabs, print out a teb instead.
 			formattedMessage += " "
 			columnCountdown --
 		}
@@ -66,9 +67,9 @@ func (err Error) Error () (formattedMessage string) {
 			// TODO: for tabs, print out 8 of these instead.
 			formattedMessage += "-"
 		}
-		formattedMessage += "-\n"
+		formattedMessage += "^\n"
 	}
-	formattedMessage += err.message + "-\n"
+	formattedMessage += err.message + "\n"
 
 	return
 }
diff --git a/lexer/lexer.go b/lexer/lexer.go
index 040b405..742e981 100644
--- a/lexer/lexer.go
+++ b/lexer/lexer.go
@@ -1,7 +1,9 @@
 package lexer
 
 import "io"
+import "fmt"
 import "github.com/sashakoshka/arf/file"
+import "github.com/sashakoshka/arf/types"
 
 // LexingOperation holds information about an ongoing lexing operataion.
 type LexingOperation struct {
@@ -31,22 +33,62 @@ func (lexer *LexingOperation) tokenize () (err error) {
 	if err != nil { return }
 
 	for {
+		fmt.Println(string(lexer.char))
+		
 		lowercase := lexer.char >= 'a' && lexer.char <= 'z'
 		uppercase := lexer.char >= 'A' && lexer.char <= 'Z'
 		number    := lexer.char >= '0' && lexer.char <= '9'
 
 		if number {
-			// TODO: tokenize number begin
+			err = lexer.tokenizeNumberBeginning(false)
+			if err != nil { return }
 		} else if lowercase || uppercase {
-			// TODO: tokenize alpha begin
+			err = lexer.tokenizeAlphaBeginning()
+			if err != nil { return }
 		} else {
 			err = lexer.tokenizeSymbolBeginning()
-			if err != nil { return err }
+			if err != nil { return }
 		}
 
-		// TODO:  skip whitespace
+		err = lexer.skipSpaces()
+		if err != nil { return }
 	}
 
+	if lexer.tokens[len(lexer.tokens) - 1].kind != TokenKindNewline {
+		lexer.addToken(Token { kind: TokenKindNewline })
+	}
+
+	return
+}
+
+func (lexer *LexingOperation) tokenizeAlphaBeginning () (err error) {
+	got := ""
+
+	for {
+		lowercase := lexer.char >= 'a' && lexer.char <= 'z'
+		uppercase := lexer.char >= 'A' && lexer.char <= 'Z'
+		number    := lexer.char >= '0' && lexer.char <= '9'
+		if !lowercase && !uppercase && !number { break }
+
+		got += string(lexer.char)
+
+		lexer.nextRune()
+	}
+
+	token := Token { kind: TokenKindName, value: got }
+
+	if len(got) == 2 {
+		firstValid  := got[0] == 'n' || got[0] == 'r' || got[0] == 'w'
+		secondValid := got[1] == 'n' || got[1] == 'r' || got[1] == 'w'
+
+		if firstValid && secondValid {
+			token.kind  = TokenKindPermission
+			token.value = types.PermissionFrom(got)
+		}
+	}
+
+	lexer.addToken(token)
+
 	return
 }
 
@@ -55,7 +97,8 @@ func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
 	case '#':
 		// comment
 		for lexer.char != '\n' {
-			lexer.nextRune()
+			err = lexer.nextRune()
+			if err != nil { return }
 		}
 	case '\t':
 		// indent level
@@ -75,105 +118,146 @@ func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
 			lexer.addToken (Token {
 				kind: TokenKindIndent,
 			})
-			lexer.nextRune()
+			err = lexer.nextRune()
+			if err != nil { return }
 		}
 	case '\n':
 		// line break
+		lastLineEmpty := true
+		tokenIndex := len(lexer.tokens) - 1
+		for lexer.tokens[tokenIndex].kind != TokenKindNewline  {
+			if lexer.tokens[tokenIndex].kind != TokenKindIndent {
+
+				lastLineEmpty = false
+				break
+			}	
+			tokenIndex --
+		}
+
+		if lastLineEmpty {
+			lexer.tokens = lexer.tokens[:tokenIndex]
+		}
+		
 		// TODO: if last line was blank, (ony whitespace) discard.
 		lexer.addToken (Token {
 			kind: TokenKindNewline,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '"':
-		// TODO: tokenize string literal
-		lexer.nextRune()
+		err = lexer.tokenizeString(false)
 	case '\'':
-		// TODO: tokenize rune literal
-		lexer.nextRune()
+		err = lexer.tokenizeString(true)
 	case ':':
 		lexer.addToken (Token {
 			kind: TokenKindColon,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '.':
 		lexer.addToken (Token {
 			kind: TokenKindDot,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '[':
 		lexer.addToken (Token {
 			kind: TokenKindLBracket,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case ']':
 		lexer.addToken (Token {
 			kind: TokenKindRBracket,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '{':
 		lexer.addToken (Token {
 			kind: TokenKindLBrace,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '}':
 		lexer.addToken (Token {
 			kind: TokenKindRBrace,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '+':
-		lexer.addToken (Token {
-			kind: TokenKindPlus,
-		})
-		lexer.nextRune()
+		err = lexer.nextRune()
+		if err != nil { return }
+		token := Token { kind: TokenKindPlus }
+		if lexer.char == '+' {
+			token.kind = TokenKindIncrement
+		}
+		lexer.addToken(token)
+		err = lexer.nextRune()
 	case '-':
-		// TODO: tokenize dash begin
-		lexer.nextRune()
+		err = lexer.tokenizeDashBeginning()
 	case '*':
 		lexer.addToken (Token {
 			kind: TokenKindAsterisk,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '/':
 		lexer.addToken (Token {
 			kind: TokenKindSlash,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '@':
 		lexer.addToken (Token {
 			kind: TokenKindAt,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '!':
 		lexer.addToken (Token {
 			kind: TokenKindExclamation,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '%':
 		lexer.addToken (Token {
 			kind: TokenKindPercent,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '~':
 		lexer.addToken (Token {
 			kind: TokenKindTilde,
 		})
-		lexer.nextRune()
+		err = lexer.nextRune()
 	case '<':
-		// TODO: tokenize less than begin
-		lexer.nextRune()
+		err = lexer.nextRune()
+		if err != nil { return }
+		token := Token { kind: TokenKindLessThan }
+		if lexer.char == '<' {
+			token.kind = TokenKindLShift
+		}
+		lexer.addToken(token)
+		err = lexer.nextRune()
 	case '>':
-		// TODO: tokenize greater than begin
-		lexer.nextRune()
+		err = lexer.nextRune()
+		if err != nil { return }
+		token := Token { kind: TokenKindGreaterThan }
+		if lexer.char == '>' {
+			token.kind = TokenKindRShift
+		}
+		lexer.addToken(token)
+		err = lexer.nextRune()
 	case '|':
-		// TODO: tokenize bar begin
-		lexer.nextRune()
+		err = lexer.nextRune()
+		if err != nil { return }
+		token := Token { kind: TokenKindBinaryOr }
+		if lexer.char == '|' {
+			token.kind = TokenKindLogicalOr
+		}
+		lexer.addToken(token)
+		err = lexer.nextRune()
 	case '&':
-		// TODO: tokenize and begin
-		lexer.nextRune()
+		err = lexer.nextRune()
+		if err != nil { return }
+		token := Token { kind: TokenKindBinaryAnd }
+		if lexer.char == '&' {
+			token.kind = TokenKindLogicalAnd
+		}
+		lexer.addToken(token)
+		err = lexer.nextRune()
 	default:
 		err = file.NewError (
 			lexer.file.Location(), 1,
-			"unexpected character " +
+			"unexpected symbol character " +
 			string(lexer.char),
 			file.ErrorKindError)
 		return
@@ -182,10 +266,53 @@ func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
 	return
 }
 
+func (lexer *LexingOperation) tokenizeDashBeginning () (err error) {
+	err = lexer.nextRune()
+	if err != nil { return }
+
+	if lexer.char == '-' {
+		token := Token { kind: TokenKindDecrement }
+
+		err = lexer.nextRune()
+		if err != nil { return }
+
+		if lexer.char == '-' {
+			token.kind = TokenKindSeparator
+			lexer.nextRune()
+		}
+		lexer.addToken(token)
+	} else if lexer.char == '>' {
+		token := Token { kind: TokenKindReturnDirection }
+
+		err = lexer.nextRune() 
+		if err != nil { return }
+
+		lexer.addToken(token)
+	} else if lexer.char >= '0' && lexer.char <= '9' {
+		lexer.tokenizeNumberBeginning(true)
+	} else {
+		token := Token { kind: TokenKindMinus }
+		lexer.addToken(token)
+	}
+	
+	return
+}
+
+// addToken adds a new token to the lexer's token slice.
 func (lexer *LexingOperation) addToken (token Token) {
 	lexer.tokens = append(lexer.tokens, token)
 }
 
+// skipSpaces skips all space characters (not tabs or newlines)
+func (lexer *LexingOperation) skipSpaces () (err error) {
+	for lexer.char == ' ' {
+		err = lexer.nextRune()
+		if err != nil { return }
+	}
+
+	return
+}
+
 // nextRune advances the lexer to the next rune in the file.
 func (lexer *LexingOperation) nextRune () (err error) {
 	lexer.char, _, err = lexer.file.ReadRune()
diff --git a/lexer/lexer_test.go b/lexer/lexer_test.go
index 62a5791..9143521 100644
--- a/lexer/lexer_test.go
+++ b/lexer/lexer_test.go
@@ -13,10 +13,15 @@ func TestTokenizeAll (test *testing.T) {
 	}
 	
 	tokens, err := Tokenize(file)
-	test.Log("resulting error:")
-	test.Log(err.Error())
-	if err == nil {
-		test.Log("Tokenize() should have returned an error")
+
+	// print all tokens
+	for index, token := range tokens {
+		test.Log(index, "\tgot token:", token.Describe())
+	}
+	
+	if err != nil {
+		test.Log("returned error:")
+		test.Log(err.Error())
 		test.Fail()
 		return
 	}
@@ -28,10 +33,10 @@ func TestTokenizeAll (test *testing.T) {
 			External: types.ModeWrite,
 		}},
 		Token { kind: TokenKindReturnDirection },
-		Token { kind: TokenKindInt, value: -349820394 },
-		Token { kind: TokenKindUInt, value: 932748397 },
+		Token { kind: TokenKindInt, value: int64(-349820394) },
+		Token { kind: TokenKindUInt, value: uint64(932748397) },
 		Token { kind: TokenKindFloat, value: 239485.37520 },
-		Token { kind: TokenKindString, value: "hello world\n" },
+		Token { kind: TokenKindString, value: "hello world!\n" },
 		Token { kind: TokenKindRune, value: 'E' },
 		Token { kind: TokenKindName, value: "helloWorld" },
 		Token { kind: TokenKindColon },
@@ -40,6 +45,7 @@ func TestTokenizeAll (test *testing.T) {
 		Token { kind: TokenKindRBracket },
 		Token { kind: TokenKindLBrace },
 		Token { kind: TokenKindRBrace },
+		Token { kind: TokenKindNewline },
 		Token { kind: TokenKindPlus },
 		Token { kind: TokenKindMinus },
 		Token { kind: TokenKindIncrement },
@@ -58,6 +64,7 @@ func TestTokenizeAll (test *testing.T) {
 		Token { kind: TokenKindLogicalOr },
 		Token { kind: TokenKindBinaryAnd },
 		Token { kind: TokenKindLogicalAnd },
+		Token { kind: TokenKindNewline },
 	}
 
 	if len(tokens) != len(correct) {
@@ -70,6 +77,9 @@ func TestTokenizeAll (test *testing.T) {
 	for index, token := range tokens {
 		if !token.Equals(correct[index]) {
 			test.Log("token", index, "not equal")
+			test.Log (
+				"have", token.Describe(),
+				"want", correct[index].Describe())
 			test.Fail()
 			return
 		}
diff --git a/lexer/numbers.go b/lexer/numbers.go
new file mode 100644
index 0000000..a08074b
--- /dev/null
+++ b/lexer/numbers.go
@@ -0,0 +1,124 @@
+package lexer
+
+import "github.com/sashakoshka/arf/file"
+
+// tokenizeSymbolBeginning lexes a token that starts with a number.
+func (lexer *LexingOperation) tokenizeNumberBeginning (negative bool) (err error) {
+	var number   uint64
+	var fragment float64
+	var isFloat  bool
+
+	if lexer.char == '0' {
+		lexer.nextRune()
+
+		if lexer.char == 'x' {
+			lexer.nextRune()
+			number, fragment, isFloat, err = lexer.tokenizeNumber(16)
+		} else if lexer.char == 'b' {
+			lexer.nextRune()
+			number, fragment, isFloat, err = lexer.tokenizeNumber(2)
+		} else if lexer.char == '.' {
+			number, fragment, isFloat, err = lexer.tokenizeNumber(10)
+		} else if lexer.char >= '0' && lexer.char <= '9' {
+			number, fragment, isFloat, err = lexer.tokenizeNumber(8)
+		} else {
+			return file.NewError (
+				lexer.file.Location(), 1,
+				"unexpected character in number literal",
+				file.ErrorKindError)
+		}
+	} else {
+		number, fragment, isFloat, err = lexer.tokenizeNumber(10)
+	}
+
+	if err != nil { return }
+
+	token := Token { }
+
+	if isFloat {
+		floatNumber := float64(number) + fragment
+	
+		token.kind  = TokenKindFloat
+		if negative {
+			token.value = floatNumber * -1
+		} else {
+			token.value = floatNumber
+		}
+	} else {
+		if negative {
+			token.kind  = TokenKindInt
+			token.value = int64(number) * -1
+		} else {
+			token.kind  = TokenKindUInt
+			token.value = uint64(number)
+		}		
+	}
+	
+	lexer.addToken(token)
+	return
+}
+
+// runeToDigit converts a rune from 0-F to a corresponding digit, with a maximum
+// radix. If the character is invalid, or the digit is too big, it will return
+// false for worked.
+func runeToDigit (char rune, radix uint64) (digit uint64, worked bool) {
+	worked = true
+
+	if char >= '0' && char <= '9' {
+		digit = uint64(char - '0')
+	} else if char >= 'A' && char <= 'F' {
+		digit = uint64(char - 'A' + 9)
+	} else if char >= 'a' && char <= 'f' {
+		digit = uint64(char - 'a' + 9)
+	} else {
+		worked = false
+	}
+
+	if digit >= radix {
+		worked = false
+	}
+
+	return
+}
+
+// tokenizeNumber reads and tokenizes a number with the specified radix.
+func (lexer *LexingOperation) tokenizeNumber (
+	radix uint64,
+) (
+	number   uint64,
+	fragment float64,
+	isFloat  bool,
+	err      error,
+) {
+	for {
+		digit, worked := runeToDigit(lexer.char, radix)
+		if !worked { break }
+
+		number *= radix
+		number += digit
+
+		err = lexer.nextRune()
+		if err != nil { return }
+	}
+	
+	if lexer.char == '.' {
+		isFloat = true
+		err = lexer.nextRune()
+		if err != nil { return }
+
+		coef := 1 / float64(radix)
+		for {
+			digit, worked := runeToDigit(lexer.char, radix)
+			if !worked { break }
+
+			fragment += float64(digit) * coef
+			
+			coef /= float64(radix)
+
+			err = lexer.nextRune()
+			if err != nil { return }
+		}
+	}
+	
+	return
+}
diff --git a/lexer/text.go b/lexer/text.go
new file mode 100644
index 0000000..e349581
--- /dev/null
+++ b/lexer/text.go
@@ -0,0 +1,77 @@
+package lexer
+
+import "github.com/sashakoshka/arf/file"
+
+var escapeSequenceMap = map[rune] rune {
+        'a':  '\x07',
+        'b':  '\x08',
+        'f':  '\x0c',
+        'n':  '\x0a',
+        'r':  '\x0d',
+        't':  '\x09',
+        'v':  '\x0b',
+        '\'': '\'',
+        '"':  '"',
+        '\\': '\\',
+}
+
+func (lexer *LexingOperation) tokenizeString (isRuneLiteral bool) (err error) {
+	err = lexer.nextRune()
+	if err != nil { return }
+
+	got := ""
+
+	for {
+		// TODO: add hexadecimal escape codes
+		if lexer.char == '\\' {
+			err = lexer.nextRune()
+			if err != nil { return }
+	
+			actual, exists := escapeSequenceMap[lexer.char]
+			if exists {
+				got += string(actual)
+			} else {
+				err = file.NewError (
+					lexer.file.Location(), 1,
+					"unknown escape character " +
+					string(lexer.char), file.ErrorKindError)
+				return
+			}
+		} else {
+			got += string(lexer.char)
+		}
+		
+		err = lexer.nextRune()
+		if err != nil { return }
+
+		if isRuneLiteral {
+			if lexer.char == '\'' { break }
+		} else {
+			if lexer.char == '"'  { break }
+		}
+	}
+	
+	err = lexer.nextRune()
+	if err != nil { return }
+
+	token := Token { }
+
+	if isRuneLiteral {
+		if len(got) > 1 {
+			err = file.NewError (
+				lexer.file.Location(), len(got) - 1,
+				"excess data in rune literal",
+				file.ErrorKindError)
+			return
+		}
+
+		token.kind  = TokenKindRune
+		token.value = rune([]rune(got)[0])
+	} else {
+		token.kind  = TokenKindString
+		token.value = got
+	}
+
+	lexer.addToken(token)
+	return
+}
diff --git a/lexer/token.go b/lexer/token.go
index e803606..0ac8298 100644
--- a/lexer/token.go
+++ b/lexer/token.go
@@ -1,5 +1,6 @@
 package lexer
 
+import "fmt"
 import "github.com/sashakoshka/arf/file"
 
 // TokenKind is an enum represzenting what role a token has.
@@ -84,3 +85,86 @@ func (token Token) Equals (testToken Token) (match bool) {
 func (token Token) Location () (location file.Location) {
 	return token.location
 }
+
+// Describe generates a textual description of the token to be used in debug
+// logs.
+func (token Token) Describe () (description string) {
+	switch token.kind {
+	case TokenKindNewline:
+		description += "Newline"
+	case TokenKindIndent:
+		description += "Indent"
+	case TokenKindSeparator:
+		description += "Separator"
+	case TokenKindPermission:
+		description += "Permission"
+	case TokenKindReturnDirection:
+		description += "ReturnDirection"
+	case TokenKindInt:
+		description += "Int"
+	case TokenKindUInt:
+		description += "UInt"
+	case TokenKindFloat:
+		description += "Float"
+	case TokenKindString:
+		description += "String"
+	case TokenKindRune:
+		description += "Rune"
+	case TokenKindName:
+		description += "Name"
+	case TokenKindColon:
+		description += "Colon"
+	case TokenKindDot:
+		description += "Dot"
+	case TokenKindLBracket:
+		description += "LBracket"
+	case TokenKindRBracket:
+		description += "RBracket"
+	case TokenKindLBrace:
+		description += "LBrace"
+	case TokenKindRBrace:
+		description += "RBrace"
+	case TokenKindPlus:
+		description += "Plus"
+	case TokenKindMinus:
+		description += "Minus"
+	case TokenKindIncrement:
+		description += "Increment"
+	case TokenKindDecrement:
+		description += "Decrement"
+	case TokenKindAsterisk:
+		description += "Asterisk"
+	case TokenKindSlash:
+		description += "Slash"
+	case TokenKindAt:
+		description += "At"
+	case TokenKindExclamation:
+		description += "Exclamation"
+	case TokenKindPercent:
+		description += "Percent"
+	case TokenKindTilde:
+		description += "Tilde"
+	case TokenKindLessThan:
+		description += "LessThan"
+	case TokenKindLShift:
+		description += "LShift"
+	case TokenKindGreaterThan:
+		description += "GreaterThan"
+	case TokenKindRShift:
+		description += "RShift"
+	case TokenKindBinaryOr:
+		description += "BinaryOr"
+	case TokenKindLogicalOr:
+		description += "LogicalOr"
+	case TokenKindBinaryAnd:
+		description += "BinaryAnd"
+	case TokenKindLogicalAnd:
+		description += "LogicalAnd"
+	}
+
+	if token.value != nil {
+		description += fmt.Sprint(": ", token.value)
+	}
+
+	return
+}
diff --git a/types/permission.go b/types/permission.go
index ec59771..4421058 100644
--- a/types/permission.go
+++ b/types/permission.go
@@ -3,12 +3,30 @@ package types
 type Mode int
 
 const (
-	ModeRead = iota
+	ModeNone = iota
+	ModeRead
 	ModeWrite
-	ModeNone
 )
 
 type Permission struct {
 	Internal Mode
 	External Mode
 }
+
+func ModeFrom (char rune) (mode Mode) {
+	switch (char) {
+	case 'n': mode = ModeNone
+	case 'r': mode = ModeRead
+	case 'w': mode = ModeWrite	
+	}
+
+	return
+}
+
+func PermissionFrom (data string) (permission Permission) {
+	if len(data) != 2 { return }
+
+	permission.Internal = ModeFrom(rune(data[0]))
+	permission.External = ModeFrom(rune(data[1]))
+	return
+}