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 |
| uu-options | - | Uses the less popular data-lens. Error correction. | |
| 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.