Hi folks, I have a parser problem. I have a basic calculator program (Graham Hutton's from Nottingham) which contains the following code: -- Define a parser to handle the input expr :: Parser Int expr = do t <- term do symbol "+" e <- expr return (t + e) +++ return t term :: Parser Int term = do f <- factor do symbol "*" e <- expr return (f * t) +++ return f factor :: Parser Int factor = do symbol "(" e <- expr symbol ")" return e +++ natural symbol and natural are defined elsewhere and work fine, but when I compile it I get the error ERROR "C:/HUGS/Calculator.hs":66 - Undefined variable "t" I suspect I'm missing something obvious, but for the life of me I can't see it. Any suggestions? Thanks, Nik (Trying to keep a couple of weeks ahead of her students) Dr Nik Freydís Whitehead University of Akureyri, Iceland ********************************************************************* Having the moral high ground is good. Having the moral high ground and an FGMP-15 is better. *********************************************************************