lambda-options

A modern command-line parser for Haskell. https://github.com/thomaseding/lambda-options

Latest on Hackage:0.9.0.1

This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow stackage.org to host generated Haddocks.

OtherLicense licensed by Thomas Eding

lambda-options-haskell

A modern command-line parser for Haskell.

  • Easy to use. The API is expressive.
  • Easy to learn. The API is tiny and simple.
  • BSD 1-Clause License

Basic example:

import System.Environment
import Text.LambdaOptions


options :: Options IO () ()
options = do
    addOption (kw ["--help", "-h"] `text` "Display this help text.") $ do
        putStrLn "Usage:"
        getHelpDescription options >>= putStrLn
    addOption (kw "--user" `argText` "NAME" `text` "Prints name.") $ \name -> do
        putStrLn $ "Name:" ++ name
    addOption (kw "--user" `argText` "NAME AGE" `text` "Prints name and age.") $ \name age -> do
        putStrLn $ "Name:" ++ name ++ " Age:" ++ show (age :: Int)


main :: IO ()
main = do
    args <- getArgs
    case runOptions options args of
        Left (ParseFailed msg _ _) -> do
            putStrLn msg
            putStrLn $ getHelpDescription options
        Right actions -> sequence_ actions
$ example.exe --user HaskellCurry 81 --user GraceHopper
Name:HaskellCurry Age:81
Name:GraceHopper
$ example.exe -h
Usage:
 -h, --help                  Display this help text.
     --user NAME             Prints name.
     --user NAME AGE         Prints name and age.
$ example.exe --user Pythagoras LXXV
Unknown option at index 2: `LXXV'
Usage:
 -h, --help                  Display this help text.
     --user NAME             Prints name.
     --user NAME AGE         Prints name and age.
Used by 1 package:
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