How to write big file efficiently in Haskell - performance

Question

Hello i am trying to write a ~1GB file in a timely manner.Is there any recommended method.Up until now the process takes somewhere in the order of tens of minutes . Am i wrong in using Text should i use ByteString ? (I have also used String)
pt="d:\\data2.csv"
cnt=400000000
main::IO()
main=do
let payload=dat
writeWithHandle pt dat
dat::Text
dat=Data.Text.pack "0744442339"
writeWithHandle::FilePath->Text->IO()
writeWithHandle path tx=do
handle<-openFile path WriteMode
writeTimes cnt handle dat
writeTimes::Int->Handle->Text->IO()
writeTimes cnt handle payload= forM_ ([0..cnt]) (\x->Data.Text.IO.hPutStrLn handle payload)
I do not understand why it is taking so much in the order of tens of minutes.Initially i was using writeFile but i thought that would mean continously opening and closing the file for each row so i used appendFile to no avail.

Answer 1

I would recommend using a Builder for this, which is an efficient way to fill up buffers and can be written directly to a Handle.
#!/usr/bin/env stack
-- stack --resolver ghc-8.6.4 script
{-# LANGUAGE OverloadedStrings #-}
import Data.ByteString.Builder (Builder, hPutBuilder)
import Data.Foldable (fold)
import System.IO (IOMode (WriteMode), withBinaryFile)
pt :: FilePath
pt = "data2.csv"
cnt :: Int
cnt = 400000000
main :: IO ()
main = writeWithHandle pt dat
dat :: Builder
dat = "0744442339"
writeWithHandle :: FilePath -> Builder -> IO ()
writeWithHandle path tx =
withBinaryFile path WriteMode $ \h ->
hPutBuilder h $ makeBuilder cnt tx
makeBuilder :: Int -> Builder -> Builder
makeBuilder cnt payload = fold $ replicate cnt $ payload <> "\n"
You can keep payload as a Text value instead if you'd like, and convert to a Builder using encodeUtf8Builder.