(defvar haskell-packages
  '(
    flycheck
    ghc
    haskell-mode
    )
  "List of all packages to install and/or initialize. Built-in packages
which require an initialization must be listed explicitly in the list.")

(defun haskell/init-flycheck ()
  (add-hook 'haskell-mode-hook 'flycheck-mode))

(defun haskell/init-haskell-mode ()
  (require 'haskell-yas)
  (use-package haskell-mode
    :defer t
    :config
    (progn
      ;; Customization
      (custom-set-variables
       ;; Use cabal-dev for the GHCi session. Ensures our dependencies are in scope.
       '(haskell-process-type 'cabal-dev)

       ;; Use notify.el (if you have it installed) at the end of running
       ;; Cabal commands or generally things worth notifying.
       '(haskell-notify-p t)

       ;; To enable tags generation on save.
       '(haskell-tags-on-save t)

       ;; To enable stylish on save.
       '(haskell-stylish-on-save t))

      (add-hook 'haskell-mode-hook 'haskell-hook)
      (add-hook 'haskell-cabal-mode-hook 'haskell-cabal-hook)

      ;; Haskell main editing mode key bindings.
      (defun haskell-hook ()
        ;; Use simple indentation.
        (turn-on-haskell-simple-indent)
        (define-key haskell-mode-map (kbd "<return>") 'haskell-simple-indent-newline-same-col)
        (define-key haskell-mode-map (kbd "C-<return>") 'haskell-simple-indent-newline-indent)

        ;; Load the current file (and make a session if not already made).
        (define-key haskell-mode-map [?\C-c ?\C-l] 'haskell-process-load-file)
        (define-key haskell-mode-map [f5] 'haskell-process-load-file)

        ;; Switch to the REPL.
        (define-key haskell-mode-map [?\C-c ?\C-z] 'haskell-interactive-switch)
        ;; “Bring” the REPL, hiding all other windows apart from the source
        ;; and the REPL.
        (define-key haskell-mode-map (kbd "C-`") 'haskell-interactive-bring)

        ;; Build the Cabal project.
        (define-key haskell-mode-map (kbd "C-c C-c") 'haskell-process-cabal-build)
        ;; Interactively choose the Cabal command to run.
        (define-key haskell-mode-map (kbd "C-c c") 'haskell-process-cabal)

        ;; Get the type and info of the symbol at point, print it in the
        ;; message buffer.
        (define-key haskell-mode-map (kbd "C-c C-t") 'haskell-process-do-type)
        (define-key haskell-mode-map (kbd "C-c C-i") 'haskell-process-do-info)

        ;; Contextually do clever things on the space key, in particular:
        ;;   1. Complete imports, letting you choose the module name.
        ;;   2. Show the type of the symbol after the space.
        (define-key haskell-mode-map (kbd "SPC") 'haskell-mode-contextual-space)

        ;; Jump to the imports. Keep tapping to jump between import
        ;; groups. C-u f8 to jump back again.
        (define-key haskell-mode-map [f8] 'haskell-navigate-imports)

        ;; Jump to the definition of the current symbol.
        (define-key haskell-mode-map (kbd "M-.") 'haskell-mode-tag-find)

        ;; Indent the below lines on columns after the current column.
        (define-key haskell-mode-map (kbd "C-<right>")
          (lambda ()
            (interactive)
            (haskell-move-nested 1)))
        ;; Same as above but backwards.
        (define-key haskell-mode-map (kbd "C-<left>")
          (lambda ()
            (interactive)
            (haskell-move-nested -1))))

      ;; Useful to have these keybindings for .cabal files, too.
      (defun haskell-cabal-hook ()
        (define-key haskell-cabal-mode-map (kbd "C-c C-c") 'haskell-process-cabal-build)
        (define-key haskell-cabal-mode-map (kbd "C-c c") 'haskell-process-cabal)
        (define-key haskell-cabal-mode-map (kbd "C-`") 'haskell-interactive-bring)
        (define-key haskell-cabal-mode-map [?\C-c ?\C-z] 'haskell-interactive-switch)))))