Simple command args parsing and execution.

This is a small wrapper over optparse-applicative which allows combining args parsers directly with IO commands. For subcommands this can avoid type boilerplate. It also provides some compact aliases for options with their Mod's.

simple-cmd-args

A thin layer over optparse-applicative that avoids type plumbing for subcommands by using Parser (IO ()).

Various wrapper functions are also provided for common option/arg idioms.

See the library's documentation for details of all the functions provided.

Usage

$ cat readme.hs

import SimpleCmdArgs
import Control.Applicative (some)
import System.Directory

main =
  simpleCmdArgs Nothing "readme example" "Longer description..." $
  subcommands
    [ Subcommand "echo" "Print words" $
      putStrLn . unwords <$> some (strArg "STR...")
    , Subcommand "ls" "List directory" $
      ls <$> strArg "DIR"
    , Subcommand "mkdir" "Create directory" $
      mkdir <$> parentsOpt <*> strArg "DIR"
    ]
  where
    parentsOpt = switchWith 'p' "parents" "Make missing directories"

ls :: FilePath -> IO ()
ls dir =
  listDirectory dir >>= mapM_ putStrLn

mkdir :: Bool -> FilePath -> IO ()
mkdir parents =
  if parents then createDirectoryIfMissing True else createDirectory

$ ghc readme.hs
$ ./readme --help
readme example

Usage: readme COMMAND
  Longer description...

Available options:
  -h,--help                Show this help text

Available commands:
  echo                     Print words
  ls                       List directory
  mkdir                    Create directory
$ ./readme echo hello world
hello world
$ ./readme mkdir -h
Usage: readme mkdir [-p|--parents] DIR
  Create directory

Available options:
  -p,--parents             Make missing directories
  -h,--help                Show this help text

Examples

See the examples.

Hackage packages using this library: https://packdeps.haskellers.com/reverse/simple-cmd-args.