(Emacs)+haskell-multiedit

Just some code to make editing in the Haskell REPL a nicer
experience.  Allows me to write multi-line code in a separate buffer
with haskell-mode switched on, then with a simple keybinding paste and
evaluate the full code in the Haskell REPL.  The keybindings and
workflow are similar to org-src block editing (create a new buffer,
then paste the contents back into the original buffer).

Emacs/.config/emacs/config.org

@@ -2518,6 +2518,7 @@ Here I configure the REPL for Haskell via the
    (display-buffer-at-bottom)
    (window-height . 0.25))
   :config
+  (load (concat user-emacs-directory "haskell-multiedit.el"))
   (+dx/create-toggle-function
    +shell/toggle-haskell-repl
    "*haskell*"

Emacs/.config/emacs/haskell-multiedit.el

@@ -0,0 +1,66 @@
+;;; haskell-multiedit.el --- Minor mode to edit and evaluate multi-line scripts of Haskell without making a file  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2021  Aryadev Chavali
+
+;; Author: Aryadev Chavali <aryadev@aryadevchavali.com>
+;; Keywords:
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; To be used in a haskell-interactive-mode buffer.  It'll generate a
+;; new buffer with haskell-mode and this minor mode activated.  Once
+;; finished with the code, using another keybind it'll close this
+;; buffer and paste the code into haskell-interactive-mode, evaluating
+;; it all line by line with indenting and multi-line guards.
+
+;;; Code:
+
+(defvar haskell-multiedit-mode-map
+  (make-sparse-keymap))
+
+(define-minor-mode haskell-multiedit-mode
+  "Minor mode for haskell buffers generated by haskell-interactive-mode.
+Provides bindings to retrieve content back into the REPL with
+full multi-edit commands"
+  nil
+  ""
+  haskell-multiedit-mode-map)
+
+(with-eval-after-load "haskell"
+  (defun haskell-multiedit ()
+    (interactive)
+    (haskell-interactive-mode-return)
+    (switch-to-buffer "*haskell-temp*")
+    (haskell-mode)
+    (haskell-multiedit-mode))
+
+  (defun haskell-multiedit-evaluate-at-repl ()
+    (interactive)
+    (let* ((contents (buffer-string))
+           (lines (split-string contents "\n")))
+      (switch-to-buffer (haskell-session-interactive-buffer (haskell-session)))
+      (insert ":{")
+      (haskell-interactive-mode-return)
+      (mapc #'(lambda (line) (insert line) (haskell-interactive-mode-return)) lines)
+      (insert ":}")
+      (haskell-interactive-mode-return)))
+
+  (define-key haskell-interactive-mode-map (kbd "C-c '") #'haskell-multiedit)
+  (define-key haskell-multiedit-mode-map (kbd "C-c '") #'haskell-multiedit-evaluate-at-repl)
+  )
+
+(provide 'haskell-multiedit)
+;;; haskell-interactive-multiedit.el ends here