;
; this grammar recognises integer
; expressions involving +,-,*,/ and unary -
;
(
(lines		(expr |\n| lines)
		()
		)
(expr		(term exprp)
		)
(exprp		(+ term  exprp)
		(- term  exprp)
		()
		)
(term		(fact termp)
		)
(termp		(* fact  termp)
		(/ fact  termp)
		()
		)
(fact		(|(| expr |)|)
		(int )
		(- fact )
		(+ fact)
		)
(int		(digits)
		)
(digits		(digit more-digits)
		)
(more-digits	(digit more-digits)
		()
		)
(digit		(|0|) (|1|) (|2|) (|3|) (|4|) (|5|) (|6|) (|7|) (|8|) (|9|)
		)
)
