Hi, all!

When I compile my program below, ghc emits Type error.

Since the return type of foo Func is IO String and

first case statement has "return timedVal", 

I think that ghc expects the type of timedVal as String.

However, the error message shows that

ghc expects timedVal should have type IO b0.

What am I missing? 

Any comments are appreciated. 

Thanks in advance!

Chul-Woong

-- 

 

import Data.Time.LocalTime      (getZonedTime, zonedTimeToUTC)

import System.Locale            (defaultTimeLocale)

import Data.Time.Format         (formatTime)

import Data.Time.Clock         (UTCTime)

currentUTCTime :: IO UTCTime

currentUTCTime = do

zTime <- getZonedTime

        return (zonedTimeToUTC zTime)

fooFunc :: IO String

fooFunc = do

  putStrLn "Hello, world"

  barFunc "xutc"       

      where barFunc s =

                case s of

                  "apple" -> return s

                  ('x': val) -> return timedVal

                       where timedVal = case val of

                                            "utc" -> do utcTime <- currentUTCTime

                                                        formatTime defaultTimeLocale "%a" utcTime

---