一般的な Web Programmer ならば、HTTP Status code はすべて暗記していると聞きました。 しかし、僕は初心者なので、なかなか覚えきれていないので、HTTPのステータスコードをさがすのに便利なツールを用意しました。 httpstatus.hs です。インストール方法は 適当にコンパイルしてください。

httpstatus.hs

{- GHC 7.4 -}
import System.Environment
import Data.List

main = do args <- getArgs
          mapM_ (putStrLn . show) (filterStatus args)

data HttpStatus = HttpStatus {
  status::String, message::String}

instance Show HttpStatus where 
  show (HttpStatus status message) = show status ++ " : " ++ show message

toHttpStatus :: (String, String) -> HttpStatus
toHttpStatus (status, message) = HttpStatus status message

httpStatusList :: [HttpStatus]
httpStatusList = map toHttpStatus [ ("100", "Continue"),
  ("101", "Switching Protocols"),
  ("102", "Processing"),
  ("200", "OK"),
  ("201", "Created"),
  ("202", "Accepted"),
  ("203", "Non-Authoritative Information"),
  ("204", "No Content"),
  ("205", "Reset Content"),
  ("206", "Partial Content"),
  ("207", "Multi-Status"),
  ("208", "Already Reported"),
  ("300", "Multiple Choices"),
  ("301", "Moved Permanently"),
  ("302", "Found"),
  ("303", "See Other"),
  ("304", "Not Modified"),
  ("305", "Use Proxy"),
  ("307", "Temporary Redirect"),
  ("400", "Bad Request"),
  ("401", "Unauthorized"),
  ("402", "Payment Required"),
  ("403", "Forbidden"),
  ("404", "Not Found"),
  ("405", "Method Not Allowed"),
  ("406", "Not Acceptable"),
  ("407", "Proxy Authentication Required"),
  ("408", "Request Timeout"),
  ("409", "Conflict"),
  ("410", "Gone"),
  ("411", "Length Required"),
  ("412", "Precondition Failed"),
  ("413", "Request Entity Too Large"),
  ("414", "Request-URI Too Large"),
  ("415", "Unsupported Media Type"),
  ("416", "Request Range Not Satisfiable"),
  ("417", "Expectation Failed"),
  ("418", "I'm a teapot"),
  ("422", "Unprocessable Entity"),
  ("423", "Locked"),
  ("424", "Failed Dependency"),
  ("425", "No code"),
  ("426", "Upgrade Required"),
  ("428", "Precondition Required"),
  ("429", "Too Many Requests"),
  ("431", "Request Header Fields Too Large"),
  ("449", "Retry with"),
  ("500", "Internal Server Error"),
  ("501", "Not Implemented"),
  ("502", "Bad Gateway"),
  ("503", "Service Unavailable"),
  ("504", "Gateway Timeout"),
  ("505", "HTTP Version Not Supported"),
  ("506", "Variant Also Negotiates"),
  ("507", "Insufficient Storage"),
  ("509", "Bandwidth Limit Exceeded"),
  ("510", "Not Extended"),
  ("511", "Network Authentication Required") ]

matchStatus :: String -> HttpStatus -> Bool
matchStatus v = isPrefixOf v . status

filterStatus' :: String -> [HttpStatus] -> [HttpStatus]
filterStatus' = filter . matchStatus 

filterStatus :: [String] -> [HttpStatus]
filterStatus []    = httpStatusList
filterStatus (x:_) = filterStatus' x httpStatusList