examples/decode.hs

   1 -- http://www.haskellforall.com/2014/02/pipes-parse-30-lens-based-parsing.html
   2
   3 import Data.ByteString (ByteString)
   4 import Data.Text       (Text)
   5 import Lens.Family.State.Strict (zoom)
   6
   7 import Pipes
   8 import Pipes.Parse
   9 import qualified Pipes.ByteString as ByteString
  10 import qualified Pipes.Text as Text
  11 import qualified Pipes.Text.Encoding as Text
  12
  13 -- Retrieve utf8-encode `Text` chunk(s) up to 10 characters
  14 -- from the bytestring (this can have various byte lengths)
  15 parser :: Monad m => Parser ByteString m [Text]
  16 parser = zoom (Text.utf8 . Text.splitAt 10) drawAll
  17
  18 main = do
  19     (textChunks, leftovers) <- runStateT parser ByteString.stdin
  20     print textChunks
  21
  22     -- Now print the remaining `ByteString` chunks
  23     byteChunks <- evalStateT drawAll leftovers
  24     print byteChunks
  25 {-
  26 $ ./decode
  27 Hello, 世界!!!<Enter>
  28 ["Hello, \19990\30028!"]
  29 abcdefg<Enter>
  30 <Ctrl-D>
  31 ["!!\n","abcdefg\n"]
  32
  33 -}