Monad transformers are pretty good at type inference

gistfile1.hs

import Control.Monad.Identity
import Control.Monad.Error

type Scott = ErrorT String Identity Int

myf :: Int -> Scott
myf i = return i

lar :: Scott
lar = do
  x <- myf 4
  y <- myf 9
  return $ y + x

main :: IO ()
main = do
  print "lar lar lar"
  print $ runIdentity (runErrorT lar)

Let's start writing some Haskell.

Lack of subtyping makes inference easy

Here is my Scala approximation: https://gist.github.com/cvogt/bda9bd48578ccccc2d1e