2-lexer-handwritten-20240308

digit ::= [0-9]
digits ::= digit+
number ::= digits (. digits)? ( E [+-]? digits)?
letter ::= [A-Za-z]
id ::= letter (letter | digit)*
if ::= "if"
then ::= "then"
else ::= "else"
relop ::= "<" | ">" | "<=" | ">=" | "=" | "<>"