Joseph Ferano
52d3898116
Asked whether a defconst could be redefined, probed it, and got ":status ok" for a change that did nothing at all - the module was built, delivered, installed, and the program went on using the old value. That is the silent-wrongness class the house rule exists to prevent, so it is now four refusals and a fix. A defconst's value is folded into its call sites - into an array length at worst, which is decided before any type resolves - so it lives in the running program's code and not only in its storage. Refused. A defenum member is the same thing: :space is erased to an i32 literal in the caller. Refused, and compared over declarations rather than over Tast.program, which carries no enums at all for exactly that reason. A defvar's initial value is deliberately not refused. Its storage holds live state the program moved past long ago, and refusing to change the initialiser would be refusing "edit the code, keep the sand". Same Tast.global record as a defconst, opposite answers, told apart by gconst. The value comparison is structural and conservative - anything it does not recognise counts as changed. Comparing emitted text would be wrong, since Emit.const on a string allocates a name off a per-module counter and two different strings in two throwaway modules both come out as @".str.0". Third: a new global's declared initial value was being dropped. flan_dev_global callocs, so (defvar n i64 42) added at run time was silently zero. It now takes the initial value as a blob, copies it on the allocation and ignores it afterwards - the second half being where "a reload must not reset the program's state" lives. In the allocation path rather than a branch at the call site, so it cannot be got wrong at one of them. Fourth: a change with no body to publish and no storage to allocate now answers "nothing to install" instead of shipping an empty module. That is what the defconst probe actually did, and it cost the program a frame's worth of reload it did not need.
216 lines
8.8 KiB
EmacsLisp
216 lines
8.8 KiB
EmacsLisp
;;; flan-dev.el --- Talk to a running Flan program -*- lexical-binding: t; -*-
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;; The editor half of Flan's dev loop. `flan dev program.flan' compiles the
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;; program, launches it, and listens on .flan-dev.sock beside the source; this
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;; connects to that socket and sends it forms.
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;;
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;; C-c C-c recompiles the top-level form at point and installs it in the
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;; running program, at that program's next frame boundary. Call sites compiled
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;; before the new body existed follow it, and the program's state — its globals
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;; — is untouched. C-c C-k does the same for a whole buffer.
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;;
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;; The protocol is one s-expression per message, length framed. That is why
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;; there is no parser here: `prin1' writes a request and `read' reads a reply.
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;;
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;; Not implemented, because it does not exist on the other side: evaluating an
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;; expression. Redefining a name installs a body; evaluating an expression
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;; means synthesising a function around a form, calling it, and rendering the
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;; value, which is a different primitive.
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;;; Code:
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(require 'subr-x)
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(defgroup flan-dev nil
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"Talking to a running Flan program."
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:group 'flan
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:prefix "flan-dev-")
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(defcustom flan-dev-socket-name ".flan-dev.sock"
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"Name of the socket `flan dev' listens on, looked for up from the buffer."
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:type 'string)
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(defcustom flan-dev-echo-result t
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"Whether a successful evaluation reports in the echo area."
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:type 'boolean)
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(defvar flan-dev--connection nil
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"The open connection, or nil.")
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(defvar flan-dev--socket nil
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"Path of the socket `flan-dev--connection' is connected to.")
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;;; Wire
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;; Framing is a decimal byte count, a newline, then that many bytes. A message
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;; carries Flan source, which contains newlines, so a line-oriented protocol
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;; would need an escape layer that this does not. Lengths are in *bytes*, so
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;; every measurement goes through `string-bytes' and the process is raw-text —
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;; a multibyte identifier would otherwise put the reply stream out of step by
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;; exactly as many bytes as the payload has non-ASCII characters.
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(defun flan-dev--send (proc form)
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"Send FORM to PROC as one framed message."
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(let* ((payload (encode-coding-string (prin1-to-string form) 'utf-8 t)))
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(process-send-string proc (format "%d\n%s" (length payload) payload))))
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(defun flan-dev--read-reply (proc)
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"Block until PROC sends one complete framed message, and read it."
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(with-current-buffer (process-buffer proc)
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(let ((deadline (+ (float-time) 30)))
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;; The header first: digits up to a newline.
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(while (and (not (save-excursion (goto-char (point-min))
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(re-search-forward "\\`\\([0-9]+\\)\n" nil t)))
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(< (float-time) deadline))
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(accept-process-output proc 0.05))
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(goto-char (point-min))
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(unless (re-search-forward "\\`\\([0-9]+\\)\n" nil t)
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(error "flan dev: no reply"))
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(let* ((n (string-to-number (match-string 1)))
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(body-start (point)))
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(while (and (< (- (position-bytes (point-max)) (position-bytes body-start)) n)
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(< (float-time) deadline))
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(accept-process-output proc 0.05))
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(let* ((end (byte-to-position (+ (position-bytes body-start) n)))
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(text (decode-coding-string
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(encode-coding-string (buffer-substring-no-properties
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body-start end)
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'utf-8 t)
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'utf-8))
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(form (car (read-from-string text))))
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(delete-region (point-min) end)
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form)))))
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(defun flan-dev--request (form)
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"Send FORM to the connected program and return its reply."
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(let ((proc (flan-dev--live-connection)))
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(flan-dev--send proc form)
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(flan-dev--read-reply proc)))
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;;; Connection
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(defun flan-dev--find-socket ()
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"Find the daemon's socket by walking up from the current buffer."
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(let ((dir (locate-dominating-file
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(or buffer-file-name default-directory)
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flan-dev-socket-name)))
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(and dir (expand-file-name flan-dev-socket-name dir))))
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(defun flan-dev--live-connection ()
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"The open connection, or signal an error saying how to get one."
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(unless (and flan-dev--connection
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(process-live-p flan-dev--connection))
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(error "Not connected: M-x flan-connect, or start `flan dev program.flan'"))
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flan-dev--connection)
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;;;###autoload
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(defun flan-connect (&optional socket)
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"Connect to a `flan dev' daemon listening on SOCKET.
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With no argument, look for `flan-dev-socket-name' up from this buffer."
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(interactive
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(list (or (flan-dev--find-socket)
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(read-file-name "flan dev socket: "))))
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(unless socket (user-error "No %s found above this buffer" flan-dev-socket-name))
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(when (process-live-p flan-dev--connection)
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(delete-process flan-dev--connection))
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(let ((buf (get-buffer-create " *flan-dev*")))
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(with-current-buffer buf (erase-buffer) (set-buffer-multibyte nil))
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(setq flan-dev--connection
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(make-network-process
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:name "flan-dev" :buffer buf :family 'local :service socket
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:coding 'binary :noquery t))
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(setq flan-dev--socket socket))
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(let ((r (flan-dev--request '(:op "describe"))))
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(message "flan dev: connected to %s (%d functions, %d globals)"
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(abbreviate-file-name socket)
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(length (plist-get r :fns)) (length (plist-get r :globals))))
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flan-dev--connection)
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(defun flan-disconnect ()
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"Close the connection, which also ends the daemon and its program."
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(interactive)
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(when (process-live-p flan-dev--connection)
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(ignore-errors (flan-dev--request '(:op "close")))
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(delete-process flan-dev--connection))
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(setq flan-dev--connection nil)
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(message "flan dev: disconnected"))
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(defun flan-describe ()
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"Report what the running program currently defines."
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(interactive)
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(let ((r (flan-dev--request '(:op "describe"))))
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(message "flan dev: %s, %d functions, %d globals"
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(if (plist-get r :alive) "running" "exited")
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(length (plist-get r :fns)) (length (plist-get r :globals)))))
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;;; Evaluating
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(defun flan-dev--report (reply what)
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"Report REPLY, describing WHAT was sent."
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(if (equal (plist-get reply :status) "ok")
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(let ((fns (plist-get reply :fns))
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(names (plist-get reply :names))
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(note (plist-get reply :note)))
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(when flan-dev-echo-result
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(if note
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;; The daemon accepted it and had nothing to send. Say so rather
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;; than claiming an install that did not happen.
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(message "%s: %s" (if names (string-join names ", ") what) note)
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(message "%s installed in %.0fms"
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(if fns (string-join fns ", ")
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(if names (string-join names ", ") what))
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(or (plist-get reply :ms) 0)))))
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;; The daemon reports where, so put point there when it is this buffer.
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(let ((loc (plist-get reply :loc))
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(msg (plist-get reply :message)))
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(when (and loc (string-match "\\`\\(.*\\):\\([0-9]+\\):\\([0-9]+\\)\\'" loc))
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(let ((file (match-string 1 loc))
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(line (string-to-number (match-string 2 loc)))
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(col (string-to-number (match-string 3 loc))))
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(when (and buffer-file-name (file-equal-p file buffer-file-name))
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(goto-char (point-min))
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(forward-line (1- line))
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(forward-char (max 0 (1- col))))))
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(user-error "flan: %s" (or msg "rejected")))))
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(defun flan-dev--eval (code what)
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"Send CODE to the running program. WHAT names it for the echo area."
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(flan-dev--report
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(flan-dev--request
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;; buffer-file-name so an error points at the file being edited rather than
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;; at the daemon's placeholder.
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(list :op "eval" :code code :file (or buffer-file-name "<buffer>")))
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what))
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(defun flan-dev--defun-at-point ()
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"The text of the top-level form containing or preceding point."
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(save-excursion
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(end-of-defun)
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(let ((end (point)))
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(beginning-of-defun)
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(buffer-substring-no-properties (point) end))))
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;;;###autoload
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(defun flan-eval-defun ()
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"Recompile the top-level form at point and install it in the running program."
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(interactive)
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(flan-dev--eval (flan-dev--defun-at-point) "form"))
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;;;###autoload
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(defun flan-eval-buffer ()
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"Recompile every top-level form in this buffer and install them together.
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One module, not one per form: a var and the function that uses it have to
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arrive in the same load or the first refers to storage that does not exist."
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(interactive)
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(flan-dev--eval (buffer-substring-no-properties (point-min) (point-max))
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(buffer-name)))
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;;;###autoload
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(defun flan-eval-region (start end)
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"Recompile the top-level forms between START and END."
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(interactive "r")
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(flan-dev--eval (buffer-substring-no-properties start end) "region"))
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(provide 'flan-dev)
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;;; flan-dev.el ends here
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