I wanted to record the output of my program straight into a file. When I ran the code, it automatically generated a file with the output of this code instead of printing it on the screen.
A simple example:
func = do
writeFile "file.txt" show(calc)
calc = do return (1+1)
I do not even know if this is possible. I'm a beginner in Haskell and I still do not know how to use files.
You should use the writeFile function to overwrite or appendFile to add to the end, described in section 7.1 of the Haskell Report .
Correcting your example (and specifying the types):
func :: IO ()
func = writeFile "file.txt" (show calc)
calc :: Integer
calc = 1 + 1
When writing writeFile "file.txt" show(calc) , you are calling writeFile with 3 arguments: "file.txt" , show , and calc result. The above version describes the correct behavior:
writeFile "file.txt" (show calc)
calc
return in Haskell has a different meaning than most languages. It does not mean return the value as a result of the function, but rather, " inject a value into a type monadic . To "return" a value as in a conven- tional language, simply type the value you want to return:
calc = 1 + 1