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Command line option parsers

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Revision as of 09:01, 26 October 2013

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, ...
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.