Haskell Yahoo Finance命令行工具
我正在尝试使用创建一个命令行工具,它将从yahoo finance获取一个符号的引用。当我试图编译时,我收到了这个错误Haskell Yahoo Finance命令行工具,haskell,command-line-arguments,yahoo,haskell-platform,yahoo-finance,Haskell,Command Line Arguments,Yahoo,Haskell Platform,Yahoo Finance,我正在尝试使用创建一个命令行工具,它将从yahoo finance获取一个符号的引用。当我试图编译时,我收到了这个错误 Couldn't match expected type `[t0]' with actual type `IO (Maybe (Map (QuoteSymbol, QuoteField) QuoteValue))' In the return type of a c
Couldn't match expected type `[t0]'
with actual type `IO
(Maybe (Map (QuoteSymbol, QuoteField) QuoteValue))'
In the return type of a call of `getQuote'
In a stmt of a 'do' expression:
q <- getQuote [arg] ["s", "l1", "c"]
In the expression:
do { q <- getQuote [arg] ["s", "l1", ....];
case q of {
Nothing -> error "symbol not found"
Just m -> m } }
无法匹配预期的类型“[t0]”
使用实际类型'IO
(可能是(映射(QuoteSymbol,QuoteField)QuoteValue)'
在调用“getQuote”的返回类型中
在“do”表达式的stmt中:
q m}}
我刚刚开始学习haskell,这是一种非常不同但功能强大的语言,我不太明白问题出在哪里。任何帮助都将不胜感激,如果我用“haskell”的方式做这件事,如果没有任何改进,我也将不胜感激。谢谢
module Main where
import Finance.Quote.Yahoo
import Data.Time.Calendar
import Data.Map
import System( getArgs )
import System.Console.GetOpt
import Data.Maybe ( fromMaybe )
data Options = Options
{ optVerbose :: Bool
, optShowVersion :: Bool
, optOutput :: Maybe FilePath
, optInput :: Maybe FilePath
, optLibDirs :: [FilePath]
, optSymbol :: String
} deriving Show
defaultOptions = Options
{ optVerbose = False
, optShowVersion = False
, optOutput = Nothing
, optInput = Nothing
, optLibDirs = []
, optSymbol = "YHOO"
}
options :: [OptDescr (Options -> Options)]
options =
[ Option ['v'] ["verbose"]
(NoArg (\ opts -> opts { optVerbose = True }))
"chatty output on stderr"
, Option ['V','?'] ["version"]
(NoArg (\ opts -> opts { optShowVersion = True }))
"show version number"
, Option ['o'] ["output"]
(OptArg ((\ f opts -> opts { optOutput = Just f }) . fromMaybe "output")
"FILE")
"output FILE"
, Option ['c'] []
(OptArg ((\ f opts -> opts { optInput = Just f }) . fromMaybe "input")
"FILE")
"input FILE"
, Option ['L'] ["libdir"]
(ReqArg (\ d opts -> opts { optLibDirs = optLibDirs opts ++ [d] }) "DIR")
"library directory"
, Option ['s'] ["symbol"]
(ReqArg (\ s opts -> opts { optSymbol = getSymbol s }) "SYMBOL")
"symbol SYMBOL"
]
compilerOpts :: [String] -> IO (Options, [String])
compilerOpts argv =
case getOpt Permute options argv of
(o,n,[] ) -> return (foldl (flip id) defaultOptions o, n)
(_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
where header = "Usage: ic [OPTION...] files..."
main = do
args <- getArgs
compilerOpts args
getSymbol :: String -> String
getSymbol arg = do
q <- getQuote [arg] ["s", "l1", "c"]
case q of
Nothing -> error "symbol not found"
Just m -> m
modulemain其中
import Finance.Quote.Yahoo
导入Data.Time.Calendar
导入数据。映射
导入系统(getArgs)
导入System.Console.GetOpt
导入数据。可能(来自可能)
数据选项=选项
{optVerbose::Bool
,optShowVersion::Bool
,optOutput::可能是文件路径
,optInput::可能是文件路径
,optLibDirs::[FilePath]
,optSymbol::String
}衍生节目
defaultOptions=选项
{optVerbose=False
,optShowVersion=False
,光电输出=无
,optInput=Nothing
,optLibDirs=[]
,optSymbol=“YHOO”
}
选项::[OptDescr(选项->选项)]
选择权=
[选项['v'][“详细”]
(NoArg(\opts->opts{optVerbose=True}))
“stderr上的聊天输出”
,选项['V','?'][“版本”]
(NoArg(\opts->opts{optShowVersion=True}))
“显示版本号”
,选项['o'][“输出”]
(OptArg((\f opts->opts{optOutput=Just f}).fromaybe“output”)
“文件”)
“输出文件”
,选项['c'][]
(OptArg((\f opts->opts{optInput=Just f}).fromMaybe“input”)
“文件”)
“输入文件”
,选项['L'][“libdir”]
(ReqArg(\d opts->opts{optLibDirs=optLibDirs opts++[d]})“DIR”)
“库目录”
,选项['s'][“符号”]
(ReqArg(\s opts->opts{optSymbol=getSymbol s})“SYMBOL”)
“符号”
]
编译器提示::[String]->IO(选项,[String])
编译指针argv=
案例getOpt排列选项argv of
(o,n,[])->返回(foldl(翻转id)默认选项o,n)
(u,u,errs)->ioError(userError(concat errs++usageInfo头选项))
其中header=“用法:ic[选项…]文件…”
main=do
args字符串
getSymbol arg=do
q错误“未找到符号”
只是m->m
这是错误的:
getSymbol :: String -> String
getSymbol arg = do
q <- getQuote [arg] ["s", "l1", "c"]
case q of
Nothing -> error "symbol not found"
Just m -> m
getSymbol::String->String
getSymbol arg=do
q错误“未找到符号”
只是m->m
可能是:
getSymbol :: String -> IO String
getSymbol arg = do
q <- getQuote [arg] ["s", "l1", "c"]
case q of
Nothing -> fail "symbol not found"
Just m -> return m
getSymbol::String->IO字符串
getSymbol arg=do
q失败“未找到符号”
只需m->返回m
注意,我已经更改了类型签名和最后两行。(由于我已更改了getSymbol
的类型,因此无论在何处调用,都必须以不同的方式使用结果。)
部分解释:
您正在使用do
语法,这将产生一个一元值。getSymbol
的返回类型是String
,与[Char]
相同。列表是单子,所以这很好
但是,当您调用
右侧的getQuote
时,问题在于getSymbol
与选项的定义无关,因为它是一个IO
操作,从它使用getQuote
的事实可以看出:
getQuote :: [QuoteSymbol]
-> [QuoteField]
-> IO (Maybe (Map (QuoteSymbol, QuoteField) QuoteValue))
因此,当您说optSymbol=getSymbol s
时,您应该只放置字符串s。关键的一行当然应该是
(ReqArg (\ s opts -> opts { optSymbol = s }) "SYMBOL")
不是
目前,您只是在分析参数。您对optSymbol
字符串所做的操作(例如,通过getSymbol
到Yahoo了解该字符串)属于main
或需要定义的一些初步操作。这是一个进行类型检查的模块,它几乎什么都不做,表现如下:
-- $ ./yahoo -s STD.F -- Standard Chartered?
-- STD.F c -0.396 - -1.99%
-- STD.F l1 19.492
-- STD.F s STD.F
module Main where
import Finance.Quote.Yahoo
import Data.Time.Calendar
import Data.Map
import Prelude
import qualified Prelude
import System.Environment( getArgs )
import System.Console.GetOpt
import Data.Maybe ( fromMaybe )
import System.IO.Unsafe
main = do
args <- getArgs
(options, strs) <- compilerOpts args
whatIDoWithTheUsersOptions options strs
-- This is not doing much with all this user input ...
whatIDoWithTheUsersOptions :: Options -> [String] -> IO ()
whatIDoWithTheUsersOptions options strs = do
blather <- getSymbol $ optSymbol options
putStrLn blather
getSymbol :: String -> IO String
getSymbol arg = do
q <- getQuote [arg] ["s", "l1", "c"]
case q of
Nothing -> return $ "symbol " ++ arg ++ " not found"
Just m -> return $ unlines $ Prelude.map helper (toList m)
where helper ((a,b), c) = unwords [a,b,c]
data Options = Options
{ optVerbose :: Bool
, optShowVersion :: Bool
, optOutput :: Maybe FilePath
, optInput :: Maybe FilePath
, optLibDirs :: [FilePath]
, optSymbol :: String
} deriving Show
defaultOptions = Options
{ optVerbose = False
, optShowVersion = False
, optOutput = Nothing
, optInput = Nothing
, optLibDirs = []
, optSymbol = "YHOO"
}
options :: [OptDescr (Options -> Options)]
options =
[ Option ['v'] ["verbose"]
(NoArg (\ opts -> opts { optVerbose = True }))
"chatty output on stderr"
, Option ['V','?'] ["version"]
(NoArg (\ opts -> opts { optShowVersion = True }))
"show version number"
, Option ['o'] ["output"]
(OptArg ((\ f opts -> opts { optOutput = Just f }) . fromMaybe "output")
"FILE")
"output FILE"
, Option ['c'] []
(OptArg ((\ f opts -> opts { optInput = Just f }) . fromMaybe "input")
"FILE")
"input FILE"
, Option ['L'] ["libdir"]
(ReqArg (\ d opts -> opts { optLibDirs = optLibDirs opts ++ [d] }) "DIR")
"library directory"
, Option ['s'] ["symbol"]
(ReqArg (\ s opts -> opts { optSymbol = s }) "SYMBOL")
"symbol SYMBOL"
]
compilerOpts :: [String] -> IO (Options, [String])
compilerOpts argv =
case getOpt Permute options argv of
(o,n,[] ) -> return (Prelude.foldl (flip id) defaultOptions o, n)
(_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
where header = "Usage: ic [OPTION...] files..."
--$./yahoo-s标准F--渣打银行?
--标准食品成本-0.396--1.99%
--标准F l1 19.492
--标准频率标准频率
模块主要在哪里
import Finance.Quote.Yahoo
导入Data.Time.Calendar
导入数据。映射
进口序曲
进口合格前奏曲
导入System.Environment(getArgs)
导入System.Console.GetOpt
导入数据。可能(来自可能)
导入System.IO不安全
main=do
args IO()
用户选项选项strs=do的作用是什么
胡言乱语
getSymbol arg=do
q返回$“符号”++arg++“未找到”
Just m->return$unlines$Prelude.map助手(toList m)
其中helper((a,b,c)=UNWORD[a,b,c]
数据选项=选项
{optVerbose::Bool
,optShowVersion::Bool
,optOutput::可能是文件路径
,optInput::可能是文件路径
,optLibDirs::[FilePath]
,optSymbol::String
}衍生节目
defaultOptions=选项
{optVerbose=False
,optShowVersion=False
,光电输出=无
,optInput=Nothing
,optLibDirs=[]
,optSymbol=“YHOO”
}
选项::[OptDescr(选项->选项)]
选择权=
[选项['v'][“详细”]
(NoArg(\opts->opts{optVerbose=True}))
“stderr上的聊天输出”
,选项['V','?'][“版本”]
(NoArg(\opts->opts{optShowVersion=True}))
“显示版本号”
,选项['o'][“输出”]
(OptArg((\f opts->opts{optOutput=Just f}).fromaybe“output”)
“文件”)
“输出文件”
,选项['c'][]
(OptArg((\f opts->opts{optInput=Just f}).fromMaybe“input”)
“文件”)
“输入文件”
,选项['L'][“libdir”]
(ReqArg(\d opts->opts{optLibDirs=optLibDirs opts++[d]})“DIR”)
-- $ ./yahoo -s STD.F -- Standard Chartered?
-- STD.F c -0.396 - -1.99%
-- STD.F l1 19.492
-- STD.F s STD.F
module Main where
import Finance.Quote.Yahoo
import Data.Time.Calendar
import Data.Map
import Prelude
import qualified Prelude
import System.Environment( getArgs )
import System.Console.GetOpt
import Data.Maybe ( fromMaybe )
import System.IO.Unsafe
main = do
args <- getArgs
(options, strs) <- compilerOpts args
whatIDoWithTheUsersOptions options strs
-- This is not doing much with all this user input ...
whatIDoWithTheUsersOptions :: Options -> [String] -> IO ()
whatIDoWithTheUsersOptions options strs = do
blather <- getSymbol $ optSymbol options
putStrLn blather
getSymbol :: String -> IO String
getSymbol arg = do
q <- getQuote [arg] ["s", "l1", "c"]
case q of
Nothing -> return $ "symbol " ++ arg ++ " not found"
Just m -> return $ unlines $ Prelude.map helper (toList m)
where helper ((a,b), c) = unwords [a,b,c]
data Options = Options
{ optVerbose :: Bool
, optShowVersion :: Bool
, optOutput :: Maybe FilePath
, optInput :: Maybe FilePath
, optLibDirs :: [FilePath]
, optSymbol :: String
} deriving Show
defaultOptions = Options
{ optVerbose = False
, optShowVersion = False
, optOutput = Nothing
, optInput = Nothing
, optLibDirs = []
, optSymbol = "YHOO"
}
options :: [OptDescr (Options -> Options)]
options =
[ Option ['v'] ["verbose"]
(NoArg (\ opts -> opts { optVerbose = True }))
"chatty output on stderr"
, Option ['V','?'] ["version"]
(NoArg (\ opts -> opts { optShowVersion = True }))
"show version number"
, Option ['o'] ["output"]
(OptArg ((\ f opts -> opts { optOutput = Just f }) . fromMaybe "output")
"FILE")
"output FILE"
, Option ['c'] []
(OptArg ((\ f opts -> opts { optInput = Just f }) . fromMaybe "input")
"FILE")
"input FILE"
, Option ['L'] ["libdir"]
(ReqArg (\ d opts -> opts { optLibDirs = optLibDirs opts ++ [d] }) "DIR")
"library directory"
, Option ['s'] ["symbol"]
(ReqArg (\ s opts -> opts { optSymbol = s }) "SYMBOL")
"symbol SYMBOL"
]
compilerOpts :: [String] -> IO (Options, [String])
compilerOpts argv =
case getOpt Permute options argv of
(o,n,[] ) -> return (Prelude.foldl (flip id) defaultOptions o, n)
(_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
where header = "Usage: ic [OPTION...] files..."