Question

input <- readLn
 if (input == 0)
 then 
  putStr  "0" 
 else if (input ==1)
then 
  putStr  "1" 
else if (input ==2)

in this kind of senario how to use multiple putStr with in a then or else if ?

when i try getting a error

Type error in application
*** Expression     : putStr "0" putStr "0"
*** Term           : putStr
*** Type           : String -> IO ()
*** Does not match : a -> b -> c -> d

Answer 1

Use do-notation:

do
  a <- something
  if a 
  then
    do
      cmd1
      cmd2
  else
    do
      cmd3
      cmd4
  cmd5 -- this comes after the 'then' and the 'else'