Command line option parsers

From HaskellWiki
Revision as of 21:45, 31 August 2017 by Enoksrd (talk | contribs) (Say when download stats were gathered.)
Jump to navigation Jump to search

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.

Based on Hackage downloads, as of May 2017, cmdargs (126k downloads) and optparse-applicative (120k downloads) are the most popular.

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
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.

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