Elisp Higher-order Conversion to Interactive

For those not familiar with extending Emacs, when you create a function in Elisp it cannot be called directly by the user ("interactively") without declaring the function interactive. The simplest way to do this is by adding (interactive) to the top of the function definition. The interactive call can be made more complex, if needed, to ask the user interactively for input.

(defun hello-world ()
  "Example function."
  (message "hello"))

There are some handy higher-order functions in Elisp, such as compose and apply-partially. Today I wanted to bind the output of apply-partially to a key. My situation was this: I use revert-buffer often enough that it needs a binding. Also because I use it so much, I wanted it to stop asking me for confirmation. (Yes, there are other ways to do this including revert-without-query, but I wanted a general solution.) Using apply-partially I could supply the needed function arguments at keybind time.

The problem is that you can only bind interactive functions, and the output of apply-partially is not interactive. A quick way to work around this is to wrap it in an anonymous function, which also takes away the need for apply-partially.

(lambda () (interactive) (revert-buffer nil t))

I'd rather there be another higher-order function that takes a non-interactive function and creates an interactive version. Here it is,

;; ID: c7db6dec-e7ab-3b0f-bf26-0fa268674c6c
(defun expose (function)
  "Return an interactive version of FUNCTION."
  (lexical-let ((lex-func function))
    (lambda ()
      (funcall lex-func))))

Now the binding looks like this,

(global-set-key [f2] (expose (apply-partially 'revert-buffer nil t)))

I think this more clearly expresses my intention than the lambda wrapper would. Maybe?

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Chris Wellons

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