Where pipes IO replaces lazy IO, Producer Text m r replaces lazy Text. This module exports some convenient functions for producing and consuming pipes Text in IO, namely, readFile, writeFile, fromHandle, toHandle, stdin and stdout. Some caveats described below.

The main points are as in Pipes.ByteString

An Handle can be associated with a Producer or Consumer according as it is read or written to.

import Pipes
import qualified Pipes.Text as Text
import qualified Pipes.Text.IO as Text
import System.IO

main =
    withFile "inFile.txt"  ReadMode  $ \hIn  ->
    withFile "outFile.txt" WriteMode $ \hOut ->
    runEffect $ Text.fromHandle hIn >-> Text.toHandle hOut

To stream from files, the following is perhaps more Prelude-like (note that it uses Pipes.Safe):

import Pipes
import qualified Pipes.Text as Text
import qualified Pipes.Text.IO as Text
import Pipes.Safe

main = runSafeT $ runEffect $ Text.readFile "inFile.txt" >-> Text.writeFile "outFile.txt"

Finally, you can stream to and from stdin and stdout using the predefined stdin and stdout pipes, as with the following "echo" program:

main = runEffect $ Text.stdin >-> Text.stdout

The operations exported here are a convenience, like the similar operations in Data.Text.IO (or rather, Data.Text.Lazy.IO, since, again, Producer Text m r is 'effectful text' and something like the pipes equivalent of lazy Text.)

• Like the functions in Data.Text.IO, they attempt to work with the system encoding.
• Like the functions in Data.Text.IO, they significantly slower than ByteString operations. Where you know what encoding you are working with, use Pipes.ByteString and Pipes.Text.Encoding instead, e.g. view utf8 Bytes.stdin instead of Text.stdin
• Like the functions in Data.Text.IO , they use Text exceptions, not the standard Pipes protocols.

Something like

 view utf8 . Bytes.fromHandle :: Handle -> Producer Text IO (Producer ByteString m ()) 

yields a stream of Text, and follows standard pipes protocols by reverting to (i.e. returning) the underlying byte stream upon reaching any decoding error. (See especially the pipes-binary package.)

By contrast, something like

Text.fromHandle :: Handle -> Producer Text IO () 

supplies a stream of text returning '()', which is convenient for many tasks, but violates the pipes pipes-binary approach to decoding errors and throws an exception of the kind characteristic of the text library instead.