Re: [Haskell-cafe] Parser problem continued

15 Mar 2005


      On Tue, Mar 15, 2005 at 03:44:55PM -0000, Nicola Whitehead wrote:
...
perhaps like this:
...
expr = do t <- term
          (do symbol "+"
              e <- expr
              return (t+e)
          )
          +++
          (return t)
although I think you may also want a 'try' before the first alternative.
No, that still gives the same undefined variable error. :(
Sometimes I prefer to write such code in a lispy way:

expr = do t <- term
          ((+++)
              (do symbol "+"
                  e <- expr
                  return (t+e))
              (return t))

Best regards
Tomasz

Re: [Haskell-cafe] Parser problem continued

Tomasz Zielonka