Haskell语言学习笔记(75)Conduit
安装 conduit
$ cabal install conduit
Installed conduit-1.3.0.3
Prelude> import Conduit
Prelude Conduit>
Conduit
Conduit 是一个处理流的库。
Prelude Conduit> :{
Prelude Conduit| print $ runConduitPure
$ yieldMany [1..10]
.| mapC (+ 1)
.| sinkList
Prelude Conduit| :}
[2,3,4,5,6,7,8,9,10,11]
应用实例
{-# LANGUAGE ExtendedDefaultRules #-}
import Conduit
magic :: Int -> IO Int
magic x = do
putStrLn $ "I'm doing magic with " ++ show x
return $ x * 2
main :: IO ()
main = do
putStrLn "List version:"
mapM magic (take 10 [1..]) >>= mapM_ print . takeWhile (< 18)
putStrLn ""
putStrLn "Conduit version:"
runConduit
$ yieldMany [1..]
.| takeC 10
.| mapMC magic
.| takeWhileC (< 18)
.| mapM_C print
List version:
I'm doing magic with 1
I'm doing magic with 2
I'm doing magic with 3
I'm doing magic with 4
I'm doing magic with 5
I'm doing magic with 6
I'm doing magic with 7
I'm doing magic with 8
I'm doing magic with 9
I'm doing magic with 10
2
4
6
8
10
12
14
16
Conduit version:
I'm doing magic with 1
2
I'm doing magic with 2
4
I'm doing magic with 3
6
I'm doing magic with 4
8
I'm doing magic with 5
10
I'm doing magic with 6
12
I'm doing magic with 7
14
I'm doing magic with 8
16
I'm doing magic with 9