Haskell exercise

misc.hs

{-- XXX Your definition of `checkChar` is okay, but the abstraction itself
 -- is very odd.  It is fine as an exercise of using "do" notation and
 -- `return`. In real code though explicit statements are both short and
 -- expressive (see lines 21-22).
checkChar :: IO Bool
checkChar = do
    c <- getChar
    return (c == 'y')
--}

-- XXX There is a name for this operation -- "cons";
-- see [https://en.wikipedia.org/wiki/Cons].
-- Haskell has cons operator -- `(:)`.
-- addList = (:)
addList :: a -> [a] -> [a]  -- XXX Note that the type is not limited to `Int`.
addList y xs = y:xs

main :: IO ()  -- XXX Surround `::` with spaces from both sides.
main = do
    putStr "Enter char: "
    c <- getChar
    putStrLn $ if c == 'y' then "TRUE" else "FALSE"  -- XXX `if` expression gets evaluated and `putStrLn` uses its result.

    -- XXX `let` statement is unnecessary here. `print [1, 2]` would do.
    let l = [1, 2]
    print l  -- XXX `$` is not needed here.
    let m = addList 3 l
    print m