It should print out its first argument via a call to puts().

echo.hs

type MainFunction = Function (Int32 -> Ptr (Ptr Word8) -> IO Int32)

buildReaderFun :: String -> CodeGenModule (MainFunction)
buildReaderFun nm  = do
  puts <- newNamedFunction ExternalLinkage "puts" :: 
    TFunction (Ptr Word8 -> IO Word32)
  let callPuts format = (
        createNamedFunction ExternalLinkage "main" $ 
        \ argc argv -> do
          tmp <- getElementPtr (argv ::Value (Ptr Word8))  
                 (0 :: Int32,  ())
          call puts tmp -- Throw away return value.
          ret (0 :: Int32)) :: CodeGenModule (MainFunction)

  withStringNul nm callPuts 

/research/phd/libmet/Listener.hs:1:0:
Couldn't match expected type Word8' against inferred typePtr Word8'
Expected type: Value (Ptr Word8) -> CodeGenFunction r Terminate
Inferred type: Value (Ptr (Ptr Word8)) -> b'
When using functional dependencies to combine
FunctionArgs (a -> b) (Value a -> b') r,
arising from the dependency f -> g r' in the instance declaration at <no location info> FunctionArgs (Ptr (Ptr Word8) -> IO Int32) (Value (Ptr Word8) -> CodeGenFunction r Terminate) (CodeGenFunction r ()), arising from a use ofcreateNamedFunction'