Streams.hs

------------------------------------------------------------------------
-- |
-- Module           : What4.Utils.Streams
-- Description      : IO stream utilities
-- Copyright        : (c) Galois, Inc 2013-2020
-- License          : BSD3
-- Maintainer       : Joe Hendrix <jhendrix@galois.com>
-- Stability        : provisional
------------------------------------------------------------------------
module What4.Utils.Streams
( logErrorStream
) where

import qualified Data.ByteString.UTF8 as UTF8
import qualified System.IO.Streams as Streams

-- | Write from input stream to a logging function.
logErrorStream :: Streams.InputStream UTF8.ByteString
               -> (String -> IO ()) -- ^ Logging function
               -> IO ()
logErrorStream err_stream logFn = do
  -- Have err_stream log complete lines to logLn
  let write_err Nothing = return ()
      write_err (Just b) = logFn b
  err_output <- Streams.makeOutputStream write_err
  lns <- Streams.map UTF8.toString =<< Streams.lines err_stream
  Streams.connect lns err_output