bug#29763: New Feature: Remove unneeded eval-expression in minibuffer-history

[Robert Weiner <rsw@gnu.org>]

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For as long as I can remember, I have wanted the minibuffer history to
strip the eval-expression wrapper around expressions that I enter by
invoking eval-expression with M-:.  I want this because the wrapper
adds a lot of visual noise when searching for a specific expression and
makes it much harder to edit the expression and get trailing parentheses
right.

So if I enter:

  M-: (/ 1.0 9) RET

then C-x ESC ESC shows me:

  (eval-expression (quote (/ 1.0 9)) nil nil 127)

but I want to see just the expression that I want to reuse or edit:

  (/ 1.0 9)

This small patch against Emacs 27.0.50  gives me that; it does the same
removal for commands already in the history if you load the change in
the middle of an Emacs session.  Please consider adding it to Emacs; it is
already improving my productivity.

Bob

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*** simple-orig.el.gz	2017-12-17 22:54:50.000000000 -0500
--- simple.el.gz	2017-12-17 22:54:50.000000000 -0500
***************
*** 1563,1572 ****
--- 1563,1580 ----
                          (eval-expression-print-format (car values)))))
            (when str (princ str out)))))))
  
+ (defun minibuffer-history-edit-element (elt)
+   "Automatically simplify ELT if possible, e.g. removing eval-expression."
+   (or (and (consp elt) (eq (car elt) 'eval-expression)
+ 	   ;; Remove eval-expression wrapper and leave just the expression.
+ 	   (cadadr elt))
+       elt))
+ 
  (defun edit-and-eval-command (prompt command)
    "Prompting with PROMPT, let user edit COMMAND and eval result.
  COMMAND is a Lisp expression.  Let user edit that expression in
  the minibuffer, then read and evaluate the result."
+   (setq command (minibuffer-history-edit-element command))
    (let ((command
  	 (let ((print-level nil)
  	       (minibuffer-history-sexp-flag (1+ (minibuffer-depth))))
***************
*** 1601,1606 ****
--- 1609,1615 ----
  	newcmd)
      (if elt
  	(progn
+ 	  (setq elt (minibuffer-history-edit-element elt))
  	  (setq newcmd
  		(let ((print-level nil)
  		      (minibuffer-history-position arg)
***************
*** 2070,2075 ****
--- 2079,2085 ----
  	   (setq minibuffer-text-before-history nil))
  	  (t (setq elt (nth (1- minibuffer-history-position)
  			    (symbol-value minibuffer-history-variable)))))
+     (setq elt (minibuffer-history-edit-element elt))
      (insert
       (if (and (eq minibuffer-history-sexp-flag (minibuffer-depth))
  	      (not minibuffer-returned-to-present))