Function declaration in let..in expression causes error

[halfzebra]

Super cool project! 👍

Here's a little bug I found:

f =
  let
    foo b =
      b
  in
    1

-- (Err (["expected end of input"]),{ input = "f x =\n let\n foo b =\n b\n in\n 1\n", position = 42 })