[Haskell-cafe] handling non-string command line arguments

S. Doaitse Swierstra doaitse at swierstra.net
Wed Jul 2 21:58:05 UTC 2014

You can use http://hackage.haskell.org/package/uu-options, designed to parser command line options. It even allows for combining various elements on the command line into a single option field. 
See the second half of the paper mentioned on hackage for examples of its use.

Since the parsers make use of uu-parsinglib the user gets "autocorrection" and nice error messages for free.


On 28 Jun 2014, at 21:28 , Johan Larson <johan.g.larson at gmail.com> wrote:

> 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
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