:set -XTemplateHaskell
import Language.Haskell.TH
let seeType n = do VarI _ t _ _ <- reify n; runIO $ putStrLn $ show t; [| return True |]
let f = undefined :: Int -> Int
let g = undefined :: [Int]
let h = undefined :: (Int, Int)
$(seeType (mkName "f"))
$(seeType (mkName "g"))
$(seeType (mkName "h"))