lexer foo_lexer {

    @trivia()
    Whitespace <- p"[ \n\r\t]+"

    family alphanumericals {
        Def <- "def"
        Var <- "var"
    }

    family alphanumericals {
        Error <- "error"
        Example <- "example"
        Null <- "null"

        KwA <- "kwA"
        KwB <- "kwB"
        KwC <- "kwC"
        KwD <- "kwD"
        KwE <- "kwE"
        KwF <- "kwF"
    }


    family punctuation {
        Comma <- ","
        Dot <- "."
        Semicolon <- ";"
        Colon <- ":"
        LPar <- "("
        RPar <- ")"
        LBrace <- "{"
        RBrace <- "}"
        Equal <- or("=" | ":=")
        Plus <- "+"
    }

    Minus <- "-"
    LessThan <- "<"
    LessThanOrEqual <- "<="
    GreaterThan <- ">"
    GreaterThanOrEqual <- ">="

    @unparsing_spacing(with=alphanumericals)
    family alphanumericals {
        Number <- p"[0-9]+|0x[0-9a-f]+"
        @symbol()
        Identifier <- p"[a-zA-Z_][a-zA-Z0-9_]*"
    }

    String <- p"\"[^\"]*\""

    family comments {
        @with_unparsing_newline
        @trivia(comment=true)
        Comment <- p"#(.?)+"
    }

}