Using Haskell to output a UTF-8-encoded ByteString

Question

utf8-string supports bytestrings.

import Prelude hiding (putStr)
import Data.ByteString.Char8 (putStr)
import Data.ByteString.UTF8 (fromString)

main :: IO ()
main = putStr $ fromString "čušpajž日本語"

bytestrings are strings of bytes. When they're output, they will be truncated to 8 bits, as it describes in the documentation for Data.ByteString.Char8. You'll need to explicitly convert them to utf8 - via the utf8-string package on Hackage, which contains support for bytestrings.

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However, as of 2011, you should use the text package, for fast, packed unicode output. GHC truncating Unicode character output

Your example becomes a lot simpler:

{-# LANGUAGE OverloadedStrings #-}

import qualified Data.Text    as T
import qualified Data.Text.IO as T

main = T.putStrLn "čušpajž日本語"

Like so:

$ runhaskell A.hs
čušpajž日本語