RE: Confusing error message in case of layout-related syntax erro r
Simon Marlow <[EMAIL PROTECTED]> wrote, > > For > > > > foo = let > > x = (1, 2 > > y = 3 > > in > > fst x + y > > > > GHC 4.04 gives me > > > > Main.hs:3: parse error on input `' > > > > Interesting, but not very informative ;-) > > I know about this one, but haven't got around to fixing it yet. The parse > error is on a semicolon generated by the layout system, as you probably > guessed, which is why there's no token available to print in the error > message. Any thoughts on what a suitable error message should be? I'd > thought something along the lines of > > Main.hs:3: parse error on input ';' (inserted by layout) That's the right error message for me, but I guess a newbie will still be confused. How about tagging on one of the `probable cause' message - something along the lines of Incomplete expression on previous line or incorrect indentation of the current line. Cheers, Manuel
Re: Confusing error message in case of layout-related syntax erro r
Simon wrote: > I know about this one, but haven't got around to fixing it yet. The parse > error is on a semicolon generated by the layout system, as you probably > guessed, which is why there's no token available to print in the error > message. Any thoughts on what a suitable error message should be? I'd > thought something along the lines of > > Main.hs:3: parse error on input ';' (inserted by layout) My students find this kind of error message (Hugs says "unexpected ';'") the most confusing and frustrating thing in all of Haskelldom. If you know that the (virtual) semicolon has been inserted by layout, how about a message like: Main.hs:3: indentation error or Main.hs:3: incorrect indentation or Main.hs:3: parse error due to incorrect indentation (I think the term "indentation" means more to them than "layout", but there might be good reasons to say "layout error" instead). Mark. Dr Mark Utting, Senior Lecturer Department of Computer Science School of Computing and Mathematical Sciences The University of Waikato Tel: +64 7 838 4791 Private Bag 3105Fax: +64 7 838 4155 HamiltonEmail: [EMAIL PROTECTED] New Zealand Web: http://www.cs.waikato.ac.nz/~marku
RE: Confusing error message in case of layout-related syntax erro r
> For > > foo = let > x = (1, 2 > y = 3 > in > fst x + y > > GHC 4.04 gives me > > Main.hs:3: parse error on input `' > > Interesting, but not very informative ;-) I know about this one, but haven't got around to fixing it yet. The parse error is on a semicolon generated by the layout system, as you probably guessed, which is why there's no token available to print in the error message. Any thoughts on what a suitable error message should be? I'd thought something along the lines of Main.hs:3: parse error on input ';' (inserted by layout) re: the multi-line string literals, this one should be easier to fix. I'll take a look at it today. Cheers, Simon
