options.generic pure example

optgen.hs

{-# LANGUAGE DeriveGeneric     #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE DeriveAnyClass #-}

module Main where

import Options.Generic
import Options.Applicative

data Bla = X | Y String
  deriving (Eq, Ord, Read, Show, Generic, ParseRecord, ParseField, ParseFields)

x :: Parser Bla
x = parseFields Nothing

y :: ParserInfo Bla
y = info x mempty

z :: ParserResult Bla
z = execParserPure defaultPrefs y []

main :: IO ()
main = print z