Thanks,
I was trying this, but it turns out my indentation was wrong; the
'then' and 'else' need to be indented under the 'if', or else it gets
confused about the do block.
Also thanks for the other solutions. I'm looking up cmdargs now.
Peter
On Thu, Dec 29, 2011 at 8:42 PM, Daniel Fischer
On Thursday 29 December 2011, 21:25:31, Peter Hall wrote:
If I have something like this
main = do args <- getArgs let file = args !! 0 -- etc...
And I run it without any arguments, I get an error message like this: "Prelude.(!!): index too large".
What's the best way to handle an error like this to give a better message back to the user?
main = do args <- getArgs case args of [] -> complain _ -> happiness
or
args <- getArgs if null args then complain else happiness