使用getOpt解析Haskell中的命令行参数 [英] Parsing command line arguments in Haskell using getOpt

问题描述

我正试图自学Haskell.作为示例程序，我正在编写蜘蛛纸牌播放器.

我正在尝试使用 System.Console.GetOpt 编写命令行解析器.我知道可以为该程序进行参数解析的方法更简单，但是我想学习如何使用 GetOpt 模块，因为我预计稍后将在我将要编写的其他程序中使用它.>

我正在尝试添加一个"--help"选项，该选项仅显示用法消息，然后退出.如果"--games"选项或"--suits"选项的任何一个参数都不是有效的整数(游戏> = 1和< = 1000，suits == 1，2，我也想打印使用情况消息)，或4).我将把生成的 Options 数据类型传递给程序的其他部分.

我也收到错误消息，指出 progName 不在范围内.是不是 do 块范围内的 parseArgs 中的 case 语句?

这是我的代码，从真实世界Haskell" 和 Haskell Wiki :

 模块Main(主)，其中导入System.Console.GetOpt导入System.Environment(getArgs，getProgName)数据选项=选项{optGames :: Int，optSuits ::整数，optVerbose ::布尔派生显示defaultOptions =选项{optGames = 1，optSuits = 4，optVerbose = False}选项:: [OptDescr(选项->选项)]选项=[选项['g'] [游戏"](ReqArg(\ g opts-> opts {optGames =(read g)})"GAMES")游戏数"，选项['s'] [西装"](ReqArg(\ s opts-> opts {optSuits =(read s)})"SUITS")西装数量"，选项['v'] [详细"](NoArg(\ opts-> opts {optVerbose = True}))详细输出"]parseArgs :: IO选项parseArgs =做argv<-getArgsprogName<-getProgName的情况下的getOpt RequireOrder选项argv(opts，[]，[])->return(foldl(flip id)defaultOptions opts)(_，_，错误)->ioError(userError(concat errs ++ helpMessage))在哪里header =用法:" ++ progName ++"[OPTION ...]"helpMessage = UsageInfo标头选项main :: IO()主=做选项<-parseArgsputStrLn $显示选项 

解决方案

这是我想出的解决方案:

 模块Main(主)，其中导入Control.Monad导入Control.Monad.Error导入System.Console.GetOpt导入System.Environment(getArgs，getProgName)数据选项=选项{optGames :: Int，optSuits ::整数，optVerbose ::布尔派生显示defaultOptions =选项{optGames = 1，optSuits = 4，optVerbose = False}选项:: [OptDescr(选项->任一字符串选项)]选项=[选项['g'] [游戏"](ReqArg(\ g选择->大小写为g[(游戏，")] |游戏> = 1&&游戏< = 1000->正确的选择{optGames =游戏}_->左侧为-游戏必须为1到1000之间的数字")游戏")游戏数"，选项['s'] [西装"](ReqArg(\ s opts->例读的[(suits，")] |适合`elem` [1、2、4]->正确的选择{optSuits =西服}_->左西装必须是1、2或4") 西装")西装数量"，选项['v'] [详细"](NoArg(\ opts->右选项{optVerbose = True}))详细输出"]parseArgs :: IO选项parseArgs =做argv<-getArgsprogName<-getProgNamelet标头=用法:" ++ progName ++"[OPTION ...]"让helpMessage = usageInfo标头选项的情况下的getOpt RequireOrder选项argv(opts，[]，[])->case foldM(flip id)defaultOptions选择正确选择->退货左错误消息->ioError(userError(errorMessage ++"\ n" ++ helpMessage)(_，_，错误)->ioError(userError(concat errs ++ helpMessage))main :: IO()主=做选项<-parseArgsputStrLn $显示选项 

我该如何改善呢?

I am trying to teach myself Haskell. As a sample program, I am writing a Spider solitaire player.

I am trying to write a command line parser using System.Console.GetOpt. I know there are easier ways to do argument parsing for this program, but I want to learn how to use the GetOpt module because I anticipate needing its sophistication later in other programs that I will be writing.

I am trying to add a "--help" option that just prints a usage message and then exits. I would also like to print usage messages if either of the arguments to the "--games" option or the "--suits" option are not valid integers (games >= 1 and <= 1000, suits == 1, 2, or 4). I will be passing the resulting Options data type to other parts of my program.

I am also getting an error that progName is not in scope. Isn't the case statement in parseArgs in the scope of the do block?

Here is my code, patched together from the examples in "Real World Haskell" and the Haskell wiki:

module Main (main) where

import System.Console.GetOpt
import System.Environment(getArgs, getProgName)

data Options = Options {
    optGames :: Int
  , optSuits :: Int
  , optVerbose :: Bool
  } deriving Show

defaultOptions = Options {
    optGames  = 1
  , optSuits = 4
  , optVerbose = False
  }

options :: [OptDescr (Options -> Options)]
options =
  [ Option ['g'] ["games"]
      (ReqArg (\g opts -> opts { optGames = (read g) }) "GAMES")
      "number of games"
  , Option ['s'] ["suits"]
      (ReqArg (\s opts -> opts { optSuits = (read s) }) "SUITS")
      "number of suits"
  , Option ['v'] ["verbose"]
      (NoArg (\opts -> opts { optVerbose = True }))
      "verbose output"
  ]

parseArgs :: IO Options
parseArgs = do
  argv <- getArgs
  progName <- getProgName
  case getOpt RequireOrder options argv of
    (opts, [], []) -> return (foldl (flip id) defaultOptions opts)
    (_, _, errs) -> ioError (userError (concat errs ++ helpMessage))
  where
    header = "Usage: " ++ progName ++ " [OPTION...]"
    helpMessage = usageInfo header options

main :: IO ()
main = do
  options <- parseArgs
  putStrLn $ show options

解决方案

Here is the solution that I came up with:

module Main (main) where

import Control.Monad
import Control.Monad.Error
import System.Console.GetOpt
import System.Environment(getArgs, getProgName)

data Options = Options {
    optGames :: Int
  , optSuits :: Int
  , optVerbose :: Bool
  } deriving Show

defaultOptions = Options {
    optGames  = 1
  , optSuits = 4
  , optVerbose = False
  }

options :: [OptDescr (Options -> Either String Options)]
options =
  [ Option ['g'] ["games"]
      (ReqArg (\g opts ->
        case reads g of
          [(games, "")] | games >= 1 && games <= 1000 -> Right opts { optGames = games }
          _ -> Left "--games must be a number between 1 and 1000"
        ) "GAMES")
      "number of games"
  , Option ['s'] ["suits"]
      (ReqArg (\s opts ->
        case reads s of
          [(suits, "")] | suits `elem` [1, 2, 4] -> Right opts { optSuits = suits }
          _ -> Left "--suits must be 1, 2, or 4"
        ) "SUITS")
      "number of suits"
  , Option ['v'] ["verbose"]
      (NoArg (\opts -> Right opts { optVerbose = True }))
      "verbose output"
  ]

parseArgs :: IO Options
parseArgs = do
  argv <- getArgs
  progName <- getProgName
  let header = "Usage: " ++ progName ++ " [OPTION...]"
  let helpMessage = usageInfo header options
  case getOpt RequireOrder options argv of
    (opts, [], []) ->
      case foldM (flip id) defaultOptions opts of
        Right opts -> return opts
        Left errorMessage -> ioError (userError (errorMessage ++ "\n" ++ helpMessage))
    (_, _, errs) -> ioError (userError (concat errs ++ helpMessage))

main :: IO ()
main = do
  options <- parseArgs
  putStrLn $ show options

How can I improve this?

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