hGetLine takes a Handle and reads a line form file (or) given handle. You may get isEOFError, when handle reaches to end of file.
Prelude System.IO> :t hGetLine
hGetLine :: Handle -> IO String
Suppose ‘today.txt’ contains following data.
$ cat today.txt
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
11, 12, 13, 14, 15, 16, 17, 18, 19, 20
21, 22, 23, 24, 25, 26, 27, 28, 29, 30
31, 32, 33, 34, 35, 36, 37, 38, 39 40
Following program takes a file name as input and print the information of file line by line.
FileUtil.hs
import System.IO
readDataFrom fileHandle =
do
isFileEnd hIsEOF fileHandle
if isFileEnd
then
return ("")
else
do
info hGetLine fileHandle
putStrLn info
readDataFrom fileHandle
main =
do
putStrLn "Enter file name (Including full path) to read"
fileName getLine
fileHandle openFile fileName ReadMode
readDataFrom fileHandle
$ runghc FileUtil.hs
Enter file name (Including full path) to read
today.txt
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
11, 12, 13, 14, 15, 16, 17, 18, 19, 20
21, 22, 23, 24, 25, 26, 27, 28, 29, 30
31, 32, 33, 34, 35, 36, 37, 38, 39 40
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