emacs/lisp/progmodes/inf-lisp.el

;;; inf-lisp.el --- an inferior-lisp mode  -*- lexical-binding: t -*-

;; Copyright (C) 1988-2023 Free Software Foundation, Inc.

;; Author: Olin Shivers <shivers@cs.cmu.edu>
;; Keywords: processes, lisp

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; Hacked from tea.el by Olin Shivers (shivers@cs.cmu.edu).  8/88

;; This file defines a lisp-in-a-buffer package (inferior-lisp mode)
;; built on top of comint mode.  This version is more featureful,
;; robust, and uniform than the Emacs 18 version.  The key bindings are
;; also more compatible with the bindings of Hemlock and Zwei (the
;; Lisp Machine Emacs).

;; Since this mode is built on top of the general command-interpreter-in-
;; a-buffer mode (comint mode), it shares a common base functionality,
;; and a common set of bindings, with all modes derived from comint mode.
;; This makes these modes easier to use.

;; For documentation on the functionality provided by comint mode, and
;; the hooks available for customizing it, see the file comint.el.
;; For further information on inferior-lisp mode, see the comments below.

;; Needs fixing:
;; The load-file/compile-file default mechanism could be smarter -- it
;; doesn't know about the relationship between filename extensions and
;; whether the file is source or executable.  If you compile foo.lisp
;; with compile-file, then the next load-file should use foo.bin for
;; the default, not foo.lisp.  This is tricky to do right, particularly
;; because the extension for executable files varies so much (.o, .bin,
;; .lbin, .mo, .vo, .ao, ...).
;;
;; It would be nice if inferior-lisp (and inferior scheme, T, ...) modes
;; had a verbose minor mode wherein sending or compiling defuns, etc.
;; would be reflected in the transcript with suitable comments, e.g.
;; ";;; redefining fact".  Several ways to do this.  Which is right?
;;
;; When sending text from a source file to a subprocess, the process-mark can
;; move off the window, so you can lose sight of the process interactions.
;; Maybe I should ensure the process mark is in the window when I send
;; text to the process? Switch selectable?

;;; Code:

(require 'comint)
(require 'lisp-mode)
(require 'shell)


(defgroup inferior-lisp nil
  "Run an outside Lisp in an Emacs buffer."
  :group 'lisp
  :version "22.1")

(defcustom inferior-lisp-filter-regexp
  "\\`\\s *\\(:\\(\\w\\|\\s_\\)\\)?\\s *\\'"
  "What not to save on inferior Lisp's input history.
Input matching this regexp is not saved on the input history in Inferior Lisp
mode.  Default is whitespace followed by 0 or 1 single-letter colon-keyword
\(as in :a, :c, etc.)"
  :type 'regexp)

(defvar inferior-lisp-mode-map
  (let ((map (copy-keymap comint-mode-map)))
    (set-keymap-parent map lisp-mode-shared-map)
    (define-key map "\C-x\C-e" #'lisp-eval-last-sexp)
    (define-key map "\C-c\C-l" #'lisp-load-file)
    (define-key map "\C-c\C-k" #'lisp-compile-file)
    (define-key map "\C-c\C-a" #'lisp-show-arglist)
    (define-key map "\C-c\C-d" #'lisp-describe-sym)
    (define-key map "\C-c\C-f" #'lisp-show-function-documentation)
    (define-key map "\C-c\C-v" #'lisp-show-variable-documentation)
    map))

(easy-menu-define
  inferior-lisp-menu
  inferior-lisp-mode-map
  "Inferior Lisp Menu."
  '("Inf-Lisp"
    ["Eval Last Sexp" lisp-eval-last-sexp t]
    "--"
    ["Load File..." lisp-load-file t]
    ["Compile File..." lisp-compile-file t]
    "--"
    ["Show Arglist..." lisp-show-arglist t]
    ["Describe Symbol..." lisp-describe-sym t]
    ["Show Documentation for Function..." lisp-show-function-documentation t]
    ["Show Documentation for Variable..." lisp-show-variable-documentation t]))

;;; These commands augment Lisp mode, so you can process Lisp code in
;;; the source files.
(define-key lisp-mode-map "\M-\C-x"  #'lisp-eval-defun)     ; GNU convention
(define-key lisp-mode-map "\C-x\C-e" #'lisp-eval-last-sexp) ; GNU convention
(define-key lisp-mode-map "\C-c\C-e" #'lisp-eval-defun)
(define-key lisp-mode-map "\C-c\C-r" #'lisp-eval-region)
(define-key lisp-mode-map "\C-c\C-n" #'lisp-eval-form-and-next)
(define-key lisp-mode-map "\C-c\C-p" #'lisp-eval-paragraph)
(define-key lisp-mode-map "\C-c\C-c" #'lisp-compile-defun)
(define-key lisp-mode-map "\C-c\C-z" #'switch-to-lisp)
(define-key lisp-mode-map "\C-c\C-l" #'lisp-load-file)
(define-key lisp-mode-map "\C-c\C-k" #'lisp-compile-file)  ; "kompile" file
(define-key lisp-mode-map "\C-c\C-a" #'lisp-show-arglist)
(define-key lisp-mode-map "\C-c\C-d" #'lisp-describe-sym)
(define-key lisp-mode-map "\C-c\C-f" #'lisp-show-function-documentation)
(define-key lisp-mode-map "\C-c\C-v" #'lisp-show-variable-documentation)


;; This function exists for backwards compatibility.
;; Previous versions of this package bound commands to C-c <letter>
;; bindings, which is not allowed by the Emacs standard.

;;;  "This function binds many inferior-lisp commands to C-c <letter> bindings,
;;;where they are more accessible. C-c <letter> bindings are reserved for the
;;;user, so these bindings are non-standard. If you want them:
;;;  (with-eval-after-load 'inf-lisp 'inferior-lisp-install-letter-bindings)
;;;You can modify this function to install just the bindings you want."
(defun inferior-lisp-install-letter-bindings ()
  (define-key lisp-mode-map "\C-ce" #'lisp-eval-defun-and-go)
  (define-key lisp-mode-map "\C-cr" #'lisp-eval-region-and-go)
  (define-key lisp-mode-map "\C-cc" #'lisp-compile-defun-and-go)
  (define-key lisp-mode-map "\C-cz" #'switch-to-lisp)
  (define-key lisp-mode-map "\C-cl" #'lisp-load-file)
  (define-key lisp-mode-map "\C-ck" #'lisp-compile-file)
  (define-key lisp-mode-map "\C-ca" #'lisp-show-arglist)
  (define-key lisp-mode-map "\C-cd" #'lisp-describe-sym)
  (define-key lisp-mode-map "\C-cf" #'lisp-show-function-documentation)
  (define-key lisp-mode-map "\C-cv" #'lisp-show-variable-documentation)

  (define-key inferior-lisp-mode-map "\C-cl" #'lisp-load-file)
  (define-key inferior-lisp-mode-map "\C-ck" #'lisp-compile-file)
  (define-key inferior-lisp-mode-map "\C-ca" #'lisp-show-arglist)
  (define-key inferior-lisp-mode-map "\C-cd" #'lisp-describe-sym)
  (define-key inferior-lisp-mode-map "\C-cf" #'lisp-show-function-documentation)
  (define-key inferior-lisp-mode-map "\C-cv" #'lisp-show-variable-documentation))

(defcustom inferior-lisp-program "lisp"
  "Program name for invoking an inferior Lisp in Inferior Lisp mode."
  :type 'string)

(defcustom inferior-lisp-load-command "(load \"%s\")\n"
  "Format-string for building a Lisp expression to load a file.
This format string should use `%s' to substitute a file name
and should result in a Lisp expression that will command the inferior Lisp
to load that file.  The default works acceptably on most Lisps.
The string \"(progn (load \\\"%s\\\" :verbose nil :print t) (values))\\n\"
produces cosmetically superior output for this application,
but it works only in Common Lisp."
  :type 'string)

(defcustom inferior-lisp-prompt "^[^> \n]*>+:? *"
  "Regexp to recognize prompts in the Inferior Lisp mode.
Defaults to \"^[^> \\n]*>+:? *\", which works pretty good for Lucid, kcl,
and franz.  This variable is used to initialize `comint-prompt-regexp' in the
Inferior Lisp buffer.

This variable is only used if the variable
`comint-use-prompt-regexp' is non-nil.

More precise choices:
Lucid Common Lisp: \"^\\\\(>\\\\|\\\\(->\\\\)+\\\\) *\"
franz: \"^\\\\(->\\\\|<[0-9]*>:\\\\) *\"
kcl: \"^>+ *\""
  :type 'regexp)

(defvar inferior-lisp-buffer nil "*The current `inferior-lisp' process buffer.

MULTIPLE PROCESS SUPPORT
===========================================================================
To run multiple Lisp processes, you start the first up
with \\[inferior-lisp].  It will be in a buffer named `*inferior-lisp*'.
Rename this buffer with \\[rename-buffer].  You may now start up a new
process with another \\[inferior-lisp].  It will be in a new buffer,
named `*inferior-lisp*'.  You can switch between the different process
buffers with \\[switch-to-buffer].

Commands that send text from source buffers to Lisp processes --
like `lisp-eval-defun' or `lisp-show-arglist' -- have to choose a process
to send to, when you have more than one Lisp process around.  This
is determined by the global variable `inferior-lisp-buffer'.  Suppose you
have three inferior Lisps running:
    Buffer              Process
    foo                 inferior-lisp
    bar                 inferior-lisp<2>
    *inferior-lisp*     inferior-lisp<3>
If you do a \\[lisp-eval-defun] command on some Lisp source code,
what process do you send it to?

- If you're in a process buffer (foo, bar, or *inferior-lisp*),
  you send it to that process.
- If you're in some other buffer (e.g., a source file), you
  send it to the process attached to buffer `inferior-lisp-buffer'.
This process selection is performed by function `inferior-lisp-proc'.

Whenever \\[inferior-lisp] fires up a new process, it resets
`inferior-lisp-buffer' to be the new process's buffer.  If you only run
one process, this does the right thing.  If you run multiple
processes, you might need to change `inferior-lisp-buffer' to
whichever process buffer you want to use.")

(defvar inferior-lisp-mode-hook '()
  "Hook for customizing Inferior Lisp mode.")

(put 'inferior-lisp-mode 'mode-class 'special)

(define-derived-mode inferior-lisp-mode comint-mode "Inferior Lisp"
  "Major mode for interacting with an inferior Lisp process.
Runs a Lisp interpreter as a subprocess of Emacs, with Lisp I/O through an
Emacs buffer.  Variable `inferior-lisp-program' controls which Lisp interpreter
is run.  Variables `inferior-lisp-prompt', `inferior-lisp-filter-regexp' and
`inferior-lisp-load-command' can customize this mode for different Lisp
interpreters.

For information on running multiple processes in multiple buffers, see
documentation for variable `inferior-lisp-buffer'.

\\{inferior-lisp-mode-map}

Customization: Entry to this mode runs the hooks on `comint-mode-hook' and
`inferior-lisp-mode-hook' (in that order).

You can send text to the inferior Lisp process from other buffers containing
Lisp source.
    `switch-to-lisp' switches the current buffer to the Lisp process buffer.
    `lisp-eval-defun' sends the current defun to the Lisp process.
    `lisp-compile-defun' compiles the current defun.
    `lisp-eval-region' sends the current region to the Lisp process.
    `lisp-compile-region' compiles the current region.

    Prefixing the lisp-eval/compile-defun/region commands with
    a \\[universal-argument] causes a switch to the Lisp process buffer after sending
    the text.

Commands:\\<inferior-lisp-mode-map>
\\[comint-send-input] after the end of the process' output sends the text from the
    end of process to point.
\\[comint-send-input] before the end of the process' output copies the sexp ending at point
    to the end of the process' output, and sends it.
\\[comint-copy-old-input] copies the sexp ending at point to the end of the process' output,
    allowing you to edit it before sending it.
If `comint-use-prompt-regexp' is nil (the default), \\[comint-insert-input] on old input
   copies the entire old input to the end of the process' output, allowing
   you to edit it before sending it.  When not used on old input, or if
   `comint-use-prompt-regexp' is non-nil, \\[comint-insert-input] behaves according to
   its global binding.
\\[backward-delete-char-untabify] converts tabs to spaces as it moves back.
\\[lisp-indent-line] indents for Lisp; with argument, shifts rest
    of expression rigidly with the current line.
\\[indent-sexp] does \\[lisp-indent-line] on each line starting within following expression.
Paragraphs are separated only by blank lines.  Semicolons start comments.
If you accidentally suspend your process, use \\[comint-continue-subjob]
to continue it."
  (setq comint-prompt-regexp inferior-lisp-prompt)
  (setq mode-line-process '(":%s"))
  (lisp-mode-variables)
  (set-syntax-table lisp-mode-syntax-table)
  (setq comint-get-old-input (function lisp-get-old-input))
  (setq comint-input-filter (function lisp-input-filter)))

(defun lisp-get-old-input ()
  "Return a string containing the sexp ending at point."
  (save-excursion
    (let ((end (point)))
      (backward-sexp)
      (buffer-substring (point) end))))

(defun lisp-input-filter (str)
  "Return t if STR does not match `inferior-lisp-filter-regexp'."
  (not (string-match inferior-lisp-filter-regexp str)))

;;;###autoload
(defun inferior-lisp (cmd)
  "Run an inferior Lisp process, input and output via buffer `*inferior-lisp*'.
If there is a process already running in `*inferior-lisp*', just switch
to that buffer.

With argument, allows you to edit the command line (default is value
of `inferior-lisp-program').  Runs the hooks from
`inferior-lisp-mode-hook' (after the `comint-mode-hook' is run).

If any parts of the command name contains spaces, they should be
quoted using shell quote syntax.

\(Type \\[describe-mode] in the process buffer for a list of commands.)"
  (interactive (list (if current-prefix-arg
			 (read-string "Run lisp: " inferior-lisp-program)
		       inferior-lisp-program)))
  (if (not (comint-check-proc "*inferior-lisp*"))
      (let ((cmdlist (split-string-shell-command cmd)))
	(set-buffer (apply (function make-comint)
			   "inferior-lisp" (car cmdlist) nil (cdr cmdlist)))
	(inferior-lisp-mode)))
  (setq inferior-lisp-buffer "*inferior-lisp*")
  (pop-to-buffer "*inferior-lisp*" display-comint-buffer-action))

;;;###autoload
(defalias 'run-lisp 'inferior-lisp)

(defun lisp-eval-paragraph (&optional and-go)
  "Send the current paragraph to the inferior Lisp process.
Prefix argument means switch to the Lisp buffer afterwards."
  (interactive "P")
  (save-excursion
    (mark-paragraph)
    (lisp-eval-region (point) (mark) and-go)))

(defun lisp-eval-region (start end &optional and-go)
  "Send the current region to the inferior Lisp process.
Prefix argument means switch to the Lisp buffer afterwards."
  (interactive "r\nP")
  (comint-send-region (inferior-lisp-proc) start end)
  (comint-send-string (inferior-lisp-proc) "\n")
  (if and-go (switch-to-lisp t)))

(defun lisp-compile-string (string)
  "Send STRING to the inferior Lisp process to be compiled and executed."
  (comint-send-string
   (inferior-lisp-proc)
   (format "(funcall (compile nil (lambda () %s)))\n" string)))

(defun lisp-eval-string (string)
  "Send STRING to the inferior Lisp process to be executed."
  (comint-send-string (inferior-lisp-proc) (concat string "\n")))

(defun lisp-do-defun (do-string do-region)
  "Send the current defun to the inferior Lisp process.
The actually processing is done by DO-STRING and DO-REGION
 which determine whether the code is compiled before evaluation.
DEFVAR forms reset the variables to the init values."
  (save-excursion
    ;; Find the end of the defun this way to avoid having the region
    ;; possibly end with a comment (it there'a a comment after the
    ;; final parenthesis).
    (beginning-of-defun)
    (forward-sexp)
    (let ((end (point)) (case-fold-search t))
      (beginning-of-defun)
      (if (looking-at "(defvar")
          (funcall do-string
                   ;; replace `defvar' with `defparameter'
                   (concat "(defparameter "
                           (buffer-substring-no-properties (+ (point) 7) end)
                           "\n"))
        (funcall do-region (point) end)))))

(defun lisp-eval-defun (&optional and-go)
  "Send the current defun to the inferior Lisp process.
DEFVAR forms reset the variables to the init values.
Prefix argument means switch to the Lisp buffer afterwards."
  (interactive "P")
  (lisp-do-defun 'lisp-eval-string 'lisp-eval-region)
  (if and-go (switch-to-lisp t)))

(defun lisp-eval-last-sexp (&optional and-go)
  "Send the previous sexp to the inferior Lisp process.
Prefix argument means switch to the Lisp buffer afterwards."
  (interactive "P")
  (lisp-eval-region (save-excursion (backward-sexp) (point)) (point) and-go))

(defun lisp-eval-form-and-next ()
  "Send the previous sexp to the inferior Lisp process and move to the next one."
  (interactive "")
  (while (not (zerop (car (syntax-ppss))))
    (up-list))
  (lisp-eval-last-sexp)
  (forward-sexp))

(defun lisp-compile-region (start end &optional and-go)
  "Compile the current region in the inferior Lisp process.
Prefix argument means switch to the Lisp buffer afterwards."
  (interactive "r\nP")
  (lisp-compile-string (buffer-substring-no-properties start end))
  (if and-go (switch-to-lisp t)))

(defun lisp-compile-defun (&optional and-go)
  "Compile the current defun in the inferior Lisp process.
DEFVAR forms reset the variables to the init values.
Prefix argument means switch to the Lisp buffer afterwards."
  (interactive "P")
  (lisp-do-defun 'lisp-compile-string 'lisp-compile-region)
  (if and-go (switch-to-lisp t)))

(defun switch-to-lisp (eob-p)
  "Switch to the inferior Lisp process buffer.
With argument, positions cursor at end of buffer."
  (interactive "P")
  (if (get-buffer-process inferior-lisp-buffer)
      (let ((pop-up-frames
	     ;; Be willing to use another frame
	     ;; that already has the window in it.
	     (or pop-up-frames
		 (get-buffer-window inferior-lisp-buffer t))))
	(pop-to-buffer inferior-lisp-buffer))
      (run-lisp inferior-lisp-program))
  (when eob-p
	 (push-mark)
    (goto-char (point-max))))


;;; Now that lisp-compile/eval-defun/region takes an optional prefix arg,
;;; these commands are redundant. But they are kept around for the user
;;; to bind if he wishes, for backwards functionality, and because it's
;;; easier to type C-c e than C-u C-c C-e.

(defun lisp-eval-region-and-go (start end)
  "Send the current region to the inferior Lisp, and switch to its buffer."
  (interactive "r")
  (lisp-eval-region start end t))

(defun lisp-eval-defun-and-go ()
  "Send the current defun to the inferior Lisp, and switch to its buffer."
  (interactive)
  (lisp-eval-defun t))

(defun lisp-compile-region-and-go (start end)
  "Compile the current region in the inferior Lisp, and switch to its buffer."
  (interactive "r")
  (lisp-compile-region start end t))

(defun lisp-compile-defun-and-go ()
  "Compile the current defun in the inferior Lisp, and switch to its buffer."
  (interactive)
  (lisp-compile-defun t))

;;; A version of the form in H. Shevis' soar-mode.el package. Less robust.
;;; (defun lisp-compile-sexp (start end)
;;;   "Compile the s-expression bounded by START and END in the inferior lisp.
;;; If the sexp isn't a DEFUN form, it is evaluated instead."
;;;   (cond ((looking-at "(defun\\s +")
;;; 	 (goto-char (match-end 0))
;;; 	 (let ((name-start (point)))
;;; 	   (forward-sexp 1)
;;; 	   (process-send-string "inferior-lisp"
;;; 				(format "(compile '%s (lambda "
;;; 					(buffer-substring name-start
;;; 							  (point)))))
;;; 	 (let ((body-start (point)))
;;; 	   (goto-char start) (forward-sexp 1) ; Can't use end-of-defun.
;;; 	   (process-send-region "inferior-lisp"
;;; 				(buffer-substring body-start (point))))
;;; 	 (process-send-string "inferior-lisp" ")\n"))
;;; 	(t (lisp-eval-region start end)))))
;;;
;;; (defun lisp-compile-region (start end)
;;;   "Each s-expression in the current region is compiled (if a DEFUN)
;;; or evaluated (if not) in the inferior lisp."
;;;   (interactive "r")
;;;   (save-excursion
;;;     (goto-char start) (end-of-defun) (beginning-of-defun) ; error check
;;;     (if (< (point) start) (error "Region begins in middle of defun"))
;;;     (goto-char start)
;;;     (let ((s start))
;;;       (end-of-defun)
;;;       (while (<= (point) end) ; Zip through
;;; 	(lisp-compile-sexp s (point)) ; compiling up defun-sized chunks.
;;; 	(setq s (point))
;;; 	(end-of-defun))
;;;       (if (< s end) (lisp-compile-sexp s end)))))
;;;
;;; End of HS-style code


(defvar lisp-prev-l/c-dir/file nil
  "Record last directory and file used in loading or compiling.
This holds a cons cell of the form `(DIRECTORY . FILE)'
describing the last `lisp-load-file' or `lisp-compile-file' command.")

(defcustom lisp-source-modes '(lisp-mode)
  "Used to determine if a buffer contains Lisp source code.
If it's loaded into a buffer that is in one of these major modes, it's
considered a Lisp source file by `lisp-load-file' and `lisp-compile-file'.
Used by these commands to determine defaults."
  :type '(repeat symbol))

(defun lisp-load-file (file-name)
  "Load a Lisp file into the inferior Lisp process."
  (interactive (comint-get-source "Load Lisp file" lisp-prev-l/c-dir/file
				  lisp-source-modes nil)) ; nil because LOAD
					; doesn't need an exact name
  (comint-check-source file-name) ; Check to see if buffer needs saved.
  (setq lisp-prev-l/c-dir/file (cons (file-name-directory    file-name)
				     (file-name-nondirectory file-name)))
  (comint-send-string (inferior-lisp-proc)
		      (format inferior-lisp-load-command file-name))
  (switch-to-lisp t))


(defun lisp-compile-file (file-name)
  "Compile a Lisp file in the inferior Lisp process."
  (interactive (comint-get-source "Compile Lisp file" lisp-prev-l/c-dir/file
				  lisp-source-modes nil)) ; nil = don't need
					; suffix .lisp
  (comint-check-source file-name) ; Check to see if buffer needs saved.
  (setq lisp-prev-l/c-dir/file (cons (file-name-directory    file-name)
				     (file-name-nondirectory file-name)))
  (comint-send-string (inferior-lisp-proc) (concat "(compile-file \""
						   file-name
						   "\")\n"))
  (switch-to-lisp t))



;;; Documentation functions: function doc, var doc, arglist, and
;;; describe symbol.
;;; ===========================================================================

;;; Command strings
;;; ===============

(defvar lisp-function-doc-command
  "(let ((fn '%s))
     (format t \"Documentation for ~a:~&~a\"
	     fn (documentation fn 'function))
     (values))\n"
  "Command to query inferior Lisp for a function's documentation.")

(defvar lisp-var-doc-command
  "(let ((v '%s))
     (format t \"Documentation for ~a:~&~a\"
	     v (documentation v 'variable))
     (values))\n"
  "Command to query inferior Lisp for a variable's documentation.")

(defvar lisp-arglist-command
  "(let ((fn '%s))
     (format t \"Arglist for ~a: ~a\" fn (arglist fn))
     (values))\n"
  "Command to query inferior Lisp for a function's arglist.")

(defvar lisp-describe-sym-command
  "(describe '%s)\n"
  "Command to query inferior Lisp for a variable's documentation.")


;;; Ancillary functions
;;; ===================

;;; Reads a string from the user.
(defun lisp-symprompt (prompt default)
  (list (let ((ans (read-string (format-prompt prompt default))))
	  (if (zerop (length ans)) default ans))))


;;; Adapted from function-called-at-point in help.el.
(defun lisp-fn-called-at-pt ()
  "Return the name of the function called in the current call.
The value is nil if it can't find one."
  (condition-case nil
      (save-excursion
	(save-restriction
	  (narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
	  (backward-up-list 1)
	  (forward-char 1)
	  (let ((obj (read (current-buffer))))
	    (and (symbolp obj) obj))))
    (error nil)))


;;; Adapted from variable-at-point in help.el.
(defun lisp-var-at-pt ()
  (condition-case ()
      (save-excursion
	(forward-sexp -1)
	(skip-chars-forward "'")
	(let ((obj (read (current-buffer))))
	  (and (symbolp obj) obj)))
    (error nil)))


;;; Documentation functions: fn and var doc, arglist, and symbol describe.
;;; ======================================================================

(defun lisp-show-function-documentation (fn)
  "Send a command to the inferior Lisp to give documentation for function FN.
See variable `lisp-function-doc-command'."
  (interactive (lisp-symprompt "Function doc" (lisp-fn-called-at-pt)))
  (comint-proc-query (inferior-lisp-proc)
		     (format lisp-function-doc-command fn)))

(defun lisp-show-variable-documentation (var)
  "Send a command to the inferior Lisp to give documentation for variable VAR.
See variable `lisp-var-doc-command'."
  (interactive (lisp-symprompt "Variable doc" (lisp-var-at-pt)))
  (comint-proc-query (inferior-lisp-proc) (format lisp-var-doc-command var)))

(defun lisp-show-arglist (fn)
  "Send a query to the inferior Lisp for the arglist for function FN.
See variable `lisp-arglist-command'."
  (interactive (lisp-symprompt "Arglist" (lisp-fn-called-at-pt)))
  (comint-proc-query (inferior-lisp-proc) (format lisp-arglist-command fn)))

(defun lisp-describe-sym (sym)
  "Send a command to the inferior Lisp to describe symbol SYM.
See variable `lisp-describe-sym-command'."
  (interactive (lisp-symprompt "Describe" (lisp-var-at-pt)))
  (comint-proc-query (inferior-lisp-proc)
		     (format lisp-describe-sym-command sym)))


;;  "Returns the current inferior Lisp process.
;; See variable `inferior-lisp-buffer'."
(defun inferior-lisp-proc ()
  (let ((proc (get-buffer-process (if (derived-mode-p 'inferior-lisp-mode)
				      (current-buffer)
				    inferior-lisp-buffer))))
    (or proc
	(error "No Lisp subprocess; see variable `inferior-lisp-buffer'"))))


;; Obsolete.

(defvar inferior-lisp-load-hook nil
  "This hook is run when the library `inf-lisp' is loaded.")
(make-obsolete-variable 'inferior-lisp-load-hook
                        "use `with-eval-after-load' instead." "28.1")

(run-hooks 'inferior-lisp-load-hook)

;;; CHANGE LOG
;;; ===========================================================================
;;; 7/21/92 Jim Blandy
;;; - Changed all uses of the cmulisp name or prefix to inferior-lisp;
;;;   this is now the official inferior lisp package.  Use the global
;;;   ChangeLog from now on.
;;; 5/24/90 Olin
;;; - Split cmulisp and cmushell modes into separate files.
;;;   Not only is this a good idea, it's apparently the way it'll be rel 19.
;;; - Upgraded process sends to use comint-send-string instead of
;;;   process-send-string.
;;; - Explicit references to process "cmulisp" have been replaced with
;;;   (cmulisp-proc). This allows better handling of multiple process bufs.
;;; - Added process query and var/function/symbol documentation
;;;   commands. Based on code written by Douglas Roberts.
;;; - Added lisp-eval-last-sexp, bound to C-x C-e.
;;;
;;; 9/20/90 Olin
;;; Added a save-restriction to lisp-fn-called-at-pt. This bug and fix
;;; reported by Lennart Staflin.
;;;
;;; 3/12/90 Olin
;;; - lisp-load-file and lisp-compile-file no longer switch-to-lisp.
;;;   Tale suggested this.
;;; - Reversed this decision 7/15/91. You need the visual feedback.
;;;
;;; 7/25/91 Olin
;;; Changed all keybindings of the form C-c <letter>. These are
;;; supposed to be reserved for the user to bind. This affected
;;; mainly the compile/eval-defun/region[-and-go] commands.
;;; This was painful, but necessary to adhere to the Emacs standard.
;;; For some backwards compatibility, see the
;;;     cmulisp-install-letter-bindings
;;; function.
;;;
;;; 8/2/91 Olin
;;; - The lisp-compile/eval-defun/region commands now take a prefix arg,
;;;   which means switch-to-lisp after sending the text to the Lisp process.
;;;   This obsoletes all the -and-go commands. The -and-go commands are
;;;   kept around for historical reasons, and because the user can bind
;;;   them to key sequences shorter than C-u C-c C-<letter>.
;;; - If M-x cmulisp is invoked with a prefix arg, it allows you to
;;;   edit the command line.

(provide 'inf-lisp)

;;; inf-lisp.el ends here