racket-run vs. racket-run-module-at-point

The command named `racket-run` now runs the `main` submodule, if any,
else the file module. This behavior is like command-line racket, and,
like Dr Racket in its default mode. (Note that if a main submodule is
found and run, the REPL prompt will be "file.rkt/main>". This is
intentional. When the "magic" happens, you will see that it happened.)

The command named `racket-run-module-at-point` is what `racket-run`
used to be: It runs a specific module around point. C-c C-c is still
bound to this.

How the back end implements this: If a dynamic-requiring `(submod
"file.rkt" main)` fails, we always retry with "file.rkt". This
automatically handles the racket-run case. And it is N/A for the
racket-run-at-module case because it will only try to run `main` if
such a submodule exists in the source file.

This fixes issue #430 -- at least if you use the new `racket-run`
command, either directly or via `racket-run-and-switch-to-repl` bound
to F5 by default. If you have the default keybindings and C-c C-c to
do a racket-run-module-at-point, the hidden `main` submodule created
by lindenmayer/turtle will not run adn therefore the tree will not
print.

doc/generate.el

@@ -64,6 +64,7 @@
     racket-xp-documentation
     "Run"
     racket-run
+    racket-run-module-at-point
     racket-repl
     racket-repl-describe
     racket-repl-documentation

doc/racket-mode.texi

@@ -99,6 +99,7 @@ Explore
 Run
 
 * racket-run::
+* racket-run-module-at-point::
 * racket-repl::
 * racket-repl-describe::
 * racket-repl-documentation::
@@ -1183,6 +1184,7 @@ definitions in submodules.
 
 @menu
 * racket-run::
+* racket-run-module-at-point::
 * racket-repl::
 * racket-repl-describe::
 * racket-repl-documentation::
@@ -1198,19 +1200,19 @@ definitions in submodules.
 @node racket-run
 @subsection racket-run
 
-@kbd{C-c C-k}  or @kbd{C-c C-c} 
+@kbd{M-x}  @code{racket-run} @kbd{RET} 
+
+Save the buffer in REPL and run your program.
 
-Save and evaluate the buffer in REPL.
+Runs the @code{main} submodule, if any, otherwise the file's module.
+See also @ref{racket-run-module-at-point}.
 
 With one C-u prefix, uses errortrace for improved stack traces.
 Otherwise follows the @ref{racket-error-context} setting.
 
 With two C-u prefixes, instruments code for step debugging. See
 @ref{racket-debug-mode} and the variable @ref{racket-debuggable-files}.
 
-If point is within a Racket module form, the REPL ``enters'' that
-submodule (uses its language info and namespace).
-
 When you run again, the file is evaluated from scratch --- the
 custodian releases resources like threads and the evaluation
 environment is reset to the contents of the file. In other words,
@@ -1239,6 +1241,16 @@ To visit these locations, move point there and press RET or mouse
 click. Or, use the standard @code{next-error} and @code{previous-error}
 commands.
 
+@node racket-run-module-at-point
+@subsection racket-run-module-at-point
+
+@kbd{C-c C-k}  or @kbd{C-c C-c} 
+
+Save the buffer and run the moudule at point.
+
+Like @ref{racket-run} but runs the module around point -- either the
+file module, or, a submodule nested at ny depth.
+
 @node racket-repl
 @subsection racket-repl
 

racket-mode.el

@@ -47,7 +47,7 @@
 (defvar racket-mode-map
   (racket--easy-keymap-define
    '((("C-c C-c"
-       "C-c C-k")   racket-run)
+       "C-c C-k")   racket-run-module-at-point)
      ("C-c C-z"     racket-repl)
      ("<f5>"        racket-run-and-switch-to-repl)
      ("M-C-<f5>"    racket-racket)

racket-repl.el

@@ -235,17 +235,17 @@ buffer to run command-line Racket."
 
 ;;;###autoload
 (defun racket-run (&optional prefix)
-  "Save and evaluate the buffer in REPL.
+  "Save the buffer in REPL and run your program.
+
+Runs the `main` submodule, if any, otherwise the file's module.
+See also `racket-run-module-at-point'.
 
 With one C-u prefix, uses errortrace for improved stack traces.
 Otherwise follows the `racket-error-context' setting.
 
 With two C-u prefixes, instruments code for step debugging. See
 `racket-debug-mode' and the variable `racket-debuggable-files'.
 
-If point is within a Racket module form, the REPL \"enters\" that
-submodule (uses its language info and namespace).
-
 When you run again, the file is evaluated from scratch --- the
 custodian releases resources like threads and the evaluation
 environment is reset to the contents of the file. In other words,
@@ -268,6 +268,19 @@ include:
 To visit these locations, move point there and press RET or mouse
 click. Or, use the standard `next-error' and `previous-error'
 commands."
+  (interactive "P")
+  (racket--repl-run (list (racket--buffer-file-name) 'main)
+                    (pcase prefix
+                      (`(4)  'high)
+                      (`(16) 'debug)
+                      (_     racket-error-context))))
+
+;;;###autoload
+(defun racket-run-module-at-point (&optional prefix)
+  "Save the buffer and run the moudule at point.
+
+Like `racket-run' but runs the module around point -- either the
+file module, or, a submodule nested at ny depth."
   (interactive "P")
   (racket--repl-run (racket--what-to-run)
                     (pcase prefix

racket/fresh-line.rkt

@@ -5,24 +5,24 @@
 
 ;; Borrowed from xrepl
 
-(define last-output-port #f)
-(define last-error-port  #f)
+(define last-output-port (make-parameter #f))
+(define last-error-port  (make-parameter #f))
 
 (define (maybe-new-output-ports)
-  (define-syntax-rule (maybe last cur)
-    (unless (eq? last cur)
-      (when (and last
-                 (not (port-closed? last)))
-        (flush-output last)) ;just in case
-      (set! last cur)
-      (flush-output last)
-      (port-count-lines! last)))
-  (maybe last-output-port (current-output-port))
-  (maybe last-error-port (current-error-port)))
+  (define (maybe last cur)
+    (unless (eq? (last) (cur))
+      (when (and (last)
+                 (not (port-closed? (last))))
+        (flush-output (last))) ;just in case
+      (last (cur))
+      (flush-output (last))
+      (port-count-lines! (last))))
+  (maybe last-output-port current-output-port)
+  (maybe last-error-port current-error-port))
 
 (define (fresh-line [stderr? #f])
   (maybe-new-output-ports)
-  (define port (if stderr? last-error-port last-output-port))
+  (define port (if stderr? (last-error-port) (last-output-port)))
   (flush-output port)
   (define-values [line col pos] (port-next-location port))
   (unless (eq? col 0) (newline)))
@@ -33,5 +33,5 @@
   ;; will think that it's still right after the printout; call this
   ;; function in such cases to adjust the column to 0.
   (maybe-new-output-ports)
-  (define-values [line col pos] (port-next-location last-output-port))
-  (set-port-next-location! last-output-port line 0 pos))
+  (define-values [line col pos] (port-next-location (last-output-port)))
+  (set-port-next-location! (last-output-port) line 0 pos))

racket/repl.rkt

@@ -211,7 +211,7 @@
                             context-level
                             cmd-line-args
                             debug-files
-                            ready-thunk)       cfg)
+                            ready-thunk)   cfg)
   (define-values (dir file mod-path) (maybe-mod->dir/file/rmp maybe-mod))
   ;; Always set current-directory and current-load-relative-directory
   ;; to match the source file.
@@ -272,14 +272,21 @@
         (with-expanded-syntax-caching-evaluator maybe-mod
           (when (and maybe-mod mod-path)
             (parameterize ([current-module-name-resolver module-name-resolver-for-run])
-              ;; When exn:fail? during module load, re-run with "empty"
-              ;; module. Note: Unlikely now that we're using
-              ;; dynamic-require/some-namespace.
+              ;; When exn:fail during module load, re-run.
               (define (load-exn-handler exn)
-                (display-exn exn)
+                (define new-mod
+                  (match mod-path
+                    [`(submod ,(== file) main)
+                     (log-racket-mode-debug "~v not found, retry as ~v"
+                                            mod-path (build-path dir file))
+                     (->mod/existing (build-path dir file))]
+                    ;; Else display exn and retry as "empty" REPL.
+                    [_
+                     (display-exn exn)
+                     #f]))
                 (channel-put (current-repl-msg-chan)
-                             (struct-copy run-config cfg [maybe-mod #f]))
-                (sync never-evt))
+                             (struct-copy run-config cfg [maybe-mod new-mod]))
+                (sync never-evt)) ;mananger thread will shutdown custodian
               (with-handlers ([exn? load-exn-handler])
                 (maybe-configure-runtime mod-path) ;FIRST: see #281
                 (current-namespace