10.2. Lexical overview

small-letter	→	‘a’ | ‘b’ | … | ‘z’
cap-letter	→	‘A’ | ‘B’ | … | ‘Z’
letter	→	small-letter | cap-letter
identifier	→	(small-letter | ‘_’) {letter | digit | ‘_’}
small-keyword	→	identifier ‘:’
cap-keyword	→	cap-letter {letter | digit | ‘_’} ‘:’
argument-name	→	‘:’ identifier
op-char	→	‘!’ | ‘@’ | ‘#’ | ‘$’ | ‘%’ | ‘^’ | ‘&’ | ‘*’ | ‘-’ | ‘+’ | ‘=’ | ‘~’ | ‘/’ | ‘?’ | ‘<’ | ‘>’ | ‘,’ | ‘;’ | ‘|’ | ‘‘’ | ‘\’
operator	→	op-char {op-char}
number	→	[ ‘-’ ] (integer | real)
integer	→	[base] general-digit {general-digit}
real	→	fixed-point | float
fixed-point	→	decimal ‘.’ decimal
float	→	decimal [ ‘.’ decimal ] (‘e’ | ‘E’) [ ‘+’ | ‘-’ ] decimal
general-digit	→	digit | letter
decimal	→	digit {digit}
base	→	decimal (‘r’ | ‘R’)
string	→	‘’’ { normal-char | escape-char } ‘’’
normal-char	→	any character except ‘\’ and ‘’’
escape-char	→	‘\t’ | ‘\b’ | ‘\n’ | ‘\f’ | ‘\r’ | ‘\v’ | ‘\a’ | ‘\0’ | ‘\\’ | ‘\’’ | ‘\”’ | ‘\?’ | numeric-escape
numeric-escape	→	‘\x’ general-digit general-digit | ( ‘\d’ | ‘\o’ ) digit digit digit
comment	→	‘”’ { comment-char } ‘”’
comment-char	→	any character but ‘”’