Add simple Emacs mode

Simple mode derived from Haskell mode to not write custom parsers in this rather
early stage. Indentation is a bit janky but you can hit tab couple times to get
what you mean. Syntax highlighting works just fine.

Author: t4ccer

editor/emacs/lambda-buffers-mode.el

@@ -0,0 +1,16 @@
+;;; lambda-buffers-mode.el --- SUMMARY -*- lexical-binding: t -*-
+
+(require 'haskell-mode)
+
+(define-derived-mode lambda-buffers-mode haskell-mode "lambda-buffers"
+  "haskell-mode pretending to be lambda-buffers-mode"
+  (haskell-indent-mode)
+  (font-lock-add-keywords
+   nil
+   '(("\\<\\(record\\|sum\\|derive\\)\\>" . 'font-lock-keyword-face)))
+  (setq lsp-warn-no-matched-clients nil))
+
+(add-to-list 'auto-mode-alist '("\\.lbf$" . lambda-buffers-mode))
+
+(provide 'lambda-buffers-mode)
+;;; lambda-buffers-mode.el ends here