If you want to use getOpt, you could produce options of type 'OptDescr
(Either String (Options -> Options))', that is, for a command line
argument, either produce an error, or some modification of your
options.
It is my experience that sometimes you will need a second pass even if
you do this, because there are some errors that require the value of
multiple options to check.
Erik
On Sat, Jun 28, 2014 at 9:28 PM, Johan Larson
I've been looking at choices for parsing command line arguments, including getOpt. The examples I can find focus on string arguments, whereas I am interested in numbers. In the application at hand, it is particularly important to issue clear error messages when arguments don't parse as numbers or are out of range.
I could use getOpt as a first pass with string arguments and then turn the strings into validated numbers in a second pass, but that's a bit awkward. Alternately I could use the options records with Options -> IO Options functions. But both of these solutions treat type mismatches differently from other options errors.
Has anyone found a cleaner solution?
-- Johan Larson -- Toronto, Canada
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe