I am trying to write a simple program that reads a line from standard input, reverses it, and then prints the reversed string.

Unfortunately the native `getLine` function reads a `Costring`; I can only reverse `String`s; and there is no function that takes a `Costring` to a `String`.

How can I amend this program to compile?

```
module EchoInputReverse where

-- Agda standard library 0.7
open import Data.List using (reverse)
open import Data.String
open import Foreign.Haskell using (Unit)
open import IO.Primitive

postulate
  getLine : IO Costring

{-# COMPILED getLine getLine #-}

main : IO Unit
main = 
  getLine >>= (λ s → 
  -- NOTE: Need a (toString : Costring → String) here. Or some other strategy.
  return (toCostring (fromList (reverse (toList (toString s))))) >>= (λ s' → 
  putStrLn s'))

```