# Lexical Grammar

This chapter describes the lexical grammar of Syntek.

# Whitespace

Whitespace is all the empty space inside a Syntek program, and the tokens that get ignored by the compiler.

# Newline

A newline is indicated by a LF or CRLF character.

# Comment

A comment starts with # and ends on the first newline character. To allow a line to contain a statement and a comment, the newline character is not consumed by the comment.

# Empty lines

Empty lines are lines that do not contain any characters or only consist of whitespace, and are ignored by the compiler.

# Spaces and tabs

Space and tab characters are ignored by the compiler.

# Identifiers

Identifiers are user defined names for entities such as variables and functions. An identifier is a sequence of one or more letters, digits, and underscores. The first character in an identifier must be a letter or underscore.

Keywords and literals cannot be used as identifiers, with the exception of class properties/methods.

# valid
a
_0x0
HelloWorld

# invalid
0_

# Keywords

The following keywords are reserved and cannot be used as identifiers, with the exception of class properties/methods.

class extends new
abstract static
this super instanceof
if else
function return
async
import as
for in while
continue break yield
and or
var

# Operators and punctuation

The following characters represent operators and punctuation:

# Operators
+ - * / % ^

= ==
! !=
< <=
> >=

# Punctuation
. , [ ] ( ) { } :

# Literals

# Number

Number represents any integer and floating point value, stored according to the IEEE 754 standard. There are no explicit int and float types.

A number is a sequence of one or more digits, optionally followed by a . and one or more digits.

+ and - characters in front of a number are not part of the number.

Underscores can be placed between the digits of a number to make it more readable.

# valid
0
0.1
150
745.16
82.000001
1_851_619_781_613
7.947_137
1______1

# invalid
5.
.9
_125
612_

# String

A string literal consists of zero or more characters enclosed in single quotes. Strings can only span over a single line.

After a backslash, certain single-character escapes represent special values:

• \' single quote
• \\ backslash
• \n newline
• \r carriage return
• \t tab

# valid
''
'a'
'hello'
'\t'
'\''
'\\'

# invalid
'\'

# Boolean

A boolean can have 2 values. true and false.

true
false