insert type of Haskell functions

haskell-types.el

(defun haskell-insert-type ()
  "Insert the type of the function on the previous line.
You have to be be on the first line of the function.
Use `haskell-insert-type-infix' for infix functions.
It uses the Haskell inferior process in order to get the class constraints
as well"
  (interactive)
  (save-excursion
    (beginning-of-line)
    (zap-up-to-char 1 ?\s)
    (yank)
    (let ((func-type (inferior-haskell-type (yank-peek))))
      (beginning-of-line)
      (newline)
      (previous-line)
      (insert func-type))))

(defun haskell-insert-type-infix ()
  "Insert a type of the infix function on the previous line.
Also see `haskell-insert-type'. Note that this works by using the spaces between
arguments to determine the of function so it will fail if your first argument
contains a space, for example when matching on a String.
It uses the Haskell inferior process in order to get the class constraints
as well. Make sure you have loaded the file using `inferior-haskell-load-file'."
  (interactive)
  (save-excursion
    (beginning-of-line)
    (zap-up-to-char 1 ?\s)
    (yank)
    (forward-char)
    (zap-up-to-char 1 ?\s)
    (yank)
    (let ((func-type (inferior-haskell-type
                      (concat "(" (yank-peek) ")"))))
      (beginning-of-line)
      (newline)
      (previous-line)
      (insert func-type))))