如何在Emacs的Algol模式中实现输入时实时文本替换？

我正在为编辑采用Unicode字符编写的Algol源文件创建主模式，目前已完成基础配置：

(add-to-list 'auto-mode-alist '("\\.a60\\'" . algol-mode))

核心需求 #

• 编辑.a60文件时，输入特定连续字符序列（如<=），自动删除该序列并插入对应的Unicode字符（如≤）
• 非连续输入的相同字符序列不触发替换，仅对新输入的文本生效
• 替换后的Unicode字符需直接写入文件，而非仅在编辑器中显示替换效果
• 希望实现通用的输入文本过滤机制，能在.emacs中定义多组「输入文本-替换文本」映射（类似(substitute "&&" "∧")的形式），且无需输入转义字符

实现方案 #

尝试过global-set-key、abbrev-mode等方案，均未达到预期效果。最终采用以下代码实现需求，仅需微调部分替换规则即可：

(add-to-list 'auto-mode-alist '("\\.a60\\'" . a60-mode))

(defun a60-chars () "Convert Algol 60 symbols from ISO to Unicode."
  (interactive)
  (if (looking-back "<=") (progn (backward-delete-char 2) (insert "≤") )
  (if (looking-back ">=") (progn (backward-delete-char 2) (insert "≥") )
  ;; (if (looking-back "\\\\")  (progn (backward-delete-char 1) (insert "¬") )
  (if (looking-back "~")  (progn (backward-delete-char 1) (insert "¬") )
  (if (looking-back "&&") (progn (backward-delete-char 2) (insert "∧") )
  (if (looking-back "||") (progn (backward-delete-char 2) (insert "∨") )
  (if (looking-back "!=") (progn (backward-delete-char 2) (insert "≠") )
  (if (looking-back "==") (progn (backward-delete-char 2) (insert "≡") )
  (if (looking-back "*")  (progn (backward-delete-char 1) (insert "×") )
  ;; (if (looking-back "\\^")  (progn (backward-delete-char 1) (insert "↑") )
  (if (looking-back "<>") (progn (backward-delete-char 2) (insert "≠") )
  (if (looking-back "//") (progn (backward-delete-char 2) (insert "÷") )
)))))))))))

;; Only enable when editing .a60 files:
(add-hook 'a60-mode-hook
          '(lambda()
            (add-hook 'post-self-insert-hook #'a60-chars nil 'local)
            )
          t
)

内容的提问来源于stack exchange，提问作者Graham Toal