Haskell - How can I use pure functions inside IO functions?

Question

How can I use pure functions inside IO functions? :-/

For example: I\'m reading a file (IO function) and I want to parse its context, a string, by using a pure funct

Answer 1

Alex Horsman helped me. He said:

"Perhaps I'm misunderstanding, but that sounds pretty simple? do {x <- ioFunc; return (pureFunc x)}"

And then I solved my problem:

import System.IO  
import Data.List

getFirstPart line Nothing = line
getFirstPart line (Just index) = fst $ splitAt index line 

eliminateComment line = 
 getFirstPart line $ elemIndex ';' line

eliminateCarriageReturn line =
 getFirstPart line $ elemIndex '\r' line

eliminateEntersAndComments :: String -> String  
eliminateEntersAndComments text =
 concat $ map mapFunction $ lines text
 where
  mapFunction = (++ " ") . eliminateCarriageReturn . eliminateComment

main = do {
 contents <- readFile "../DWR-operators.txt"; 
 return (eliminateEntersAndComments contents)
}