This PR provides the ability to use Maybe a types in the datatype target of parsing. This is particularly useful for optional arguments that don't have a natural "default".
Imagine an --limit flag argument where the application operates "unbounded" if no limit is provided. You could use -1 as a default (or some other magic number) to fake this behavior, but using Maybe Int is much cleaner.
Currently this functionality requires creating a custom Argument with a custom parser. This seems like a reasonably common case for a command line application so I'd like to add first class support for it.
This PR provides the ability to use
Maybe atypes in the datatype target of parsing. This is particularly useful for optional arguments that don't have a natural "default".Imagine an
--limitflag argument where the application operates "unbounded" if no limit is provided. You could use-1as a default (or some other magic number) to fake this behavior, but usingMaybe Intis much cleaner.Currently this functionality requires creating a custom Argument with a custom parser. This seems like a reasonably common case for a command line application so I'd like to add first class support for it.