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Command line option parsers

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There are several packages that want to simplify the task of writing command line parsers. Unfortunately, they are distributed across several Hackage categories. Here is an attempt to list them:

Package Multi-mode Extensions Remark
argparser - None (though it depends on package containers, which uses extensions)
cmdargs X TemplateHaskell, SYB generics, ViewPatterns, ...
unsafePerformIO
cmdlib X SYB generics based on GetOpt
cmdtheline X FlexibleInstances (although unnecessary) shows help as man-page
console-program X (none) configure options via files
getflag - Haskell98 like GetOpt but with Unix/Plan 9 option syntax
hflags - TemplateHaskell inspired by Google's gflags, provides parsed options in top-level variables, allow to set options via environment variables
multiarg - CPP long options with multiple arguments
options X TemplateHaskell
optparse-applicative X GADT Applicative Functor; for wrong arguments it does not show a specific error message but the general usage pattern
parseargs - FlexibleInstances (although unnecessary) supports a fixed set of argument types:
Int, Integer, Float, Double, String, FileOpener
ReadArgs - OverlappingInstances, TypeOperators No options, only arguments. The argument template is derived from the requested argument tuple.
simpleargs - OverlappingInstances (although unnecessary) the same as ReadArgs
yaop - TemplateHaskell, GeneralizedNewtypeDeriving wrapper around GetOpt

The column for required Haskell extensions gives an idea of how easy it is to port the package to compilers other than GHC.