Merge branch 'master' into guile-meta

Conflicts:
	elisp/geiser-guile.el

7 files changed, 230 insertions, 158 deletions

diff --git a/elisp/geiser-completion.el b/elisp/geiser-completion.el
index d346190..f88fae6 100644
--- a/elisp/geiser-completion.el
+++ b/elisp/geiser-completion.el
@@ -228,14 +228,19 @@ we're looking for a module name.")
 Perform completion similar to Emacs' complete-symbol.
 With prefix, complete module name."
   (interactive "P")
+  (unless (geiser-syntax--symbol-at-point)
+    (error "No symbol at point"))
   (geiser--respecting-message "Retrieving completions...")
   (let* ((prefix (geiser-completion--prefix arg))
-         (result (geiser-completion--complete prefix arg))
+         (result (and prefix (geiser-completion--complete prefix arg)))
          (completions (car result))
          (partial (cdr result)))
     (cond ((null completions)
-           (geiser--respecting-message "Can't find completion for %S" prefix)
-           (geiser-completion--restore-window-cfg))
+           (if (not arg)
+               (geiser-completion--complete-symbol t)
+             (geiser--respecting-message "Can't find completion for %S"
+                                         prefix)
+             (geiser-completion--restore-window-cfg)))
           (t (insert-and-inherit (substring partial (length prefix)))
              (cond ((= (length completions) 1)
                     (geiser--respecting-message "Sole completion")
diff --git a/elisp/geiser-connection.el b/elisp/geiser-connection.el
index dfdb21d..dc669aa 100644
--- a/elisp/geiser-connection.el
+++ b/elisp/geiser-connection.el
@@ -17,6 +17,7 @@
 (require 'geiser-log)
 (require 'geiser-syntax)
 (require 'geiser-base)
+(require 'geiser-impl)
 
 (require 'comint)
 (require 'advice)
@@ -35,12 +36,13 @@
 
 ;;; Request datatype:
 
-(defun geiser-con--make-request (str cont &optional sender-buffer)
+(defun geiser-con--make-request (con str cont &optional sender-buffer)
   (list :geiser-connection-request
-        (cons :id (random))
+        (cons :id (geiser-con--connection-inc-count con))
         (cons :string str)
         (cons :continuation cont)
-        (cons :buffer (or sender-buffer (current-buffer)))))
+        (cons :buffer (or sender-buffer (current-buffer)))
+        (cons :connection con)))
 
 (defsubst geiser-con--request-p (req)
   (and (listp req) (eq (car req) :geiser-connection-request)))
@@ -57,6 +59,9 @@
 (defsubst geiser-con--request-buffer (req)
   (cdr (assoc :buffer req)))
 
+(defsubst geiser-con--request-connection (req)
+  (cdr (assoc :connection req)))
+
 (defsubst geiser-con--request-deactivate (req)
   (setcdr (assoc :continuation req) nil))
 
@@ -70,9 +75,23 @@
   (list :geiser-connection
         (cons :requests (list))
         (cons :current nil)
+        (cons :count 0)
         (cons :completed (make-hash-table :weakness 'value))
         (cons :buffer buffer)
-        (cons :timer nil)))
+        (cons :reply (geiser-con--make-reply-buffer buffer))))
+
+(defvar geiser-con--eot-regexp nil)
+(geiser-impl--register-local-variable
+ 'geiser-con--eot-regexp 'eot-regexp nil
+ "A regular expression used to detect end of transmissions.
+By default, Geiser uses the prompt regexp.")
+
+(defun geiser-con--make-reply-buffer (buffer)
+  (let ((name (concat " geiser-con-reply: " (buffer-name buffer)))
+        (eot (with-current-buffer buffer geiser-con--eot-regexp)))
+    (with-current-buffer (get-buffer-create name)
+      (setq geiser-con--eot-regexp eot)
+      (current-buffer))))
 
 (defsubst geiser-con--connection-p (c)
   (and (listp c) (eq (car c) :geiser-connection)))
@@ -89,11 +108,18 @@
 (defsubst geiser-con--connection-current-request (c)
   (cdr (assoc :current c)))
 
+(defsubst geiser-con--connection-reply-buffer (c)
+  (cdr (assoc :reply c)))
+
+(defsubst geiser-con--connection-completed (c r)
+  (geiser-con--request-deactivate r)
+  (puthash (geiser-con--request-id r) r (cdr (assoc :completed c))))
+
 (defun geiser-con--connection-clean-current-request (c)
   (let* ((cell (assoc :current c))
          (req (cdr cell)))
     (when req
-      (puthash (geiser-con--request-id req) req (cdr (assoc :completed c)))
+      (geiser-con--connection-completed c req)
       (setcdr cell nil))))
 
 (defun geiser-con--connection-add-request (c r)
@@ -104,22 +130,23 @@
   (gethash id (cdr (assoc :completed c))))
 
 (defun geiser-con--connection-pop-request (c)
-  (let ((reqs (assoc :requests c))
-        (current (assoc :current c)))
-    (setcdr current (prog1 (cadr reqs) (setcdr reqs (cddr reqs))))
-    (if (and (cdr current)
-             (geiser-con--request-deactivated-p (cdr current)))
+  (let* ((reqs (assoc :requests c))
+         (current (assoc :current c))
+         (old-current (cdr current))
+         (new-current (cadr reqs))
+         (new-reqs (cddr reqs)))
+    (when old-current (geiser-con--connection-completed c old-current))
+    (setcdr reqs new-reqs)
+    (if (and new-current
+             (geiser-con--request-deactivated-p new-current))
         (geiser-con--connection-pop-request c)
-      (cdr current))))
-
-(defun geiser-con--connection-start-timer (c)
-  (let ((cell (assoc :timer c)))
-    (when (cdr cell) (cancel-timer (cdr cell)))
-    (setcdr cell (run-at-time t 0.5 'geiser-con--process-next c))))
+      (setcdr current new-current))))
 
-(defun geiser-con--connection-cancel-timer (c)
-  (let ((cell (assoc :timer c)))
-    (when (cdr cell) (cancel-timer (cdr cell)))))
+(defun geiser-con--connection-inc-count (c)
+  (let* ((cnt (assoc :count c))
+         (new (1+ (cdr cnt))))
+    (setcdr cnt new)
+    new))
 
 
 ;;; Connection setup:
@@ -132,60 +159,55 @@
 (make-variable-buffer-local
  (defvar geiser-con--debugging-preamble-regexp nil))
 
-(defun geiser-con--is-debugging ()
-  (and geiser-con--debugging-prompt-regexp
-       geiser-con--debugging-inhibits-eval
-       comint-last-prompt-overlay
-       (string-match-p geiser-con--debugging-prompt-regexp
-                       (buffer-substring (overlay-start
-                                          comint-last-prompt-overlay)
-                                         (overlay-end
-                                          comint-last-prompt-overlay)))))
-
-(defsubst geiser-con--has-entered-debugger ()
-  (and geiser-con--debugging-prompt-regexp
-       (re-search-backward geiser-con--debugging-prompt-regexp nil t)
-       (or (null geiser-con--debugging-preamble-regexp)
-           (save-excursion
-             (re-search-backward geiser-con--debugging-preamble-regexp nil t)))))
-
-(defun geiser-con--cleanup-connection (c)
-  (geiser-con--connection-cancel-timer c))
+(defun geiser-con--is-debugging (&optional con)
+  (with-current-buffer (or (and con (geiser-con--connection-buffer con))
+                           (current-buffer))
+    (and geiser-con--debugging-prompt-regexp
+         geiser-con--debugging-inhibits-eval
+         comint-last-prompt-overlay
+         (string-match-p geiser-con--debugging-prompt-regexp
+                         (buffer-substring (overlay-start
+                                            comint-last-prompt-overlay)
+                                           (overlay-end
+                                            comint-last-prompt-overlay))))))
+
+(defsubst geiser-con--has-entered-debugger (con)
+  (with-current-buffer (geiser-con--connection-buffer con)
+    (and geiser-con--debugging-prompt-regexp
+         (re-search-backward geiser-con--debugging-prompt-regexp nil t)
+         (or (null geiser-con--debugging-preamble-regexp)
+             (save-excursion
+               (re-search-backward geiser-con--debugging-preamble-regexp
+                                   nil t))))))
+
+(defun geiser-con--connection-teardown ()
+  (when geiser-con--connection
+    (kill-buffer
+     (geiser-con--connection-reply-buffer geiser-con--connection))))
 
 (defun geiser-con--setup-connection (buffer
                                      prompt-regexp
                                      &optional debug-prompt-regexp
                                      debug-preamble-regexp)
   (with-current-buffer buffer
-    (when geiser-con--connection
-      (geiser-con--cleanup-connection geiser-con--connection))
+    (geiser-con--connection-teardown)
     (setq geiser-con--debugging-prompt-regexp debug-prompt-regexp)
     (setq geiser-con--debugging-preamble-regexp debug-preamble-regexp)
     (setq geiser-con--connection (geiser-con--make-connection buffer))
-    (geiser-con--setup-comint prompt-regexp debug-prompt-regexp)
-    (geiser-con--connection-start-timer geiser-con--connection)
-    (message "Geiser REPL up and running!")))
-
-(defun geiser-con--setup-comint (prompt-regexp debug-prompt-regexp)
-  (set (make-local-variable 'comint-redirect-insert-matching-regexp)
-       (not (null debug-prompt-regexp)))
-  (set (make-local-variable 'comint-redirect-finished-regexp)
-       (if debug-prompt-regexp
-           (format "\\(%s\\)\\|\\(%s\\)" prompt-regexp debug-prompt-regexp)
-         prompt-regexp))
-  (setq comint-prompt-regexp comint-redirect-finished-regexp)
-  (add-hook 'comint-redirect-hook 'geiser-con--comint-redirect-hook nil t))
+    (set (make-local-variable 'comint-redirect-insert-matching-regexp) t)
+    (setq comint-prompt-regexp
+	  (if debug-prompt-regexp
+	      (format "\\(%s\\)\\|\\(%s\\)" prompt-regexp debug-prompt-regexp)
+	    prompt-regexp))
+    (add-hook 'comint-redirect-hook 'geiser-con--comint-redirect-hook nil t)))
 
 
 ;;; Requests handling:
 
-(defsubst geiser-con--comint-buffer ()
-  (get-buffer-create " *geiser connection retort*"))
-
-(defun geiser-con--comint-buffer-form ()
-  (with-current-buffer (geiser-con--comint-buffer)
+(defun geiser-con--comint-buffer-form (con)
+  (with-current-buffer (geiser-con--connection-reply-buffer con)
     (goto-char (point-max))
-    (if (geiser-con--has-entered-debugger)
+    (if (geiser-con--has-entered-debugger con)
         `((error (key . geiser-debugger))
           (output . ,(buffer-substring (point-min) (point))))
       (condition-case nil
@@ -201,56 +223,52 @@
 (defun geiser-con--process-next (con)
   (when (not (geiser-con--connection-current-request con))
     (let* ((buffer (geiser-con--connection-buffer con))
-           (debug-prompt (with-current-buffer buffer
-                           geiser-con--debugging-prompt-regexp))
-           (debug-preamble (with-current-buffer buffer
-                             geiser-con--debugging-preamble-regexp))
            (req (geiser-con--connection-pop-request con))
            (str (and req (geiser-con--request-string req)))
-           (cbuf (geiser-con--comint-buffer)))
-      (if (not (buffer-live-p buffer))
-          (geiser-con--connection-cancel-timer con)
-        (when (and buffer req str)
-          (with-current-buffer cbuf
-            (setq comint-redirect-echo-input nil)
-            (setq geiser-con--debugging-prompt-regexp debug-prompt)
-            (setq geiser-con--debugging-preamble-regexp debug-preamble)
-            (delete-region (point-min) (point-max)))
-          (set-buffer buffer)
-          (if (geiser-con--is-debugging)
-              (geiser-con--request-deactivate req)
-            (geiser-log--info "<%s>: %s" (geiser-con--request-id req) str)
-            (comint-redirect-send-command (format "%s" str) cbuf nil t)))))))
+           (rbuffer (geiser-con--connection-reply-buffer con)))
+      (when (and buffer (buffer-live-p buffer) req str)
+        (with-current-buffer rbuffer
+          (delete-region (point-min) (point-max)))
+        (set-buffer buffer)
+        (if (geiser-con--is-debugging)
+            (geiser-con--connection-completed con req)
+          (geiser-log--info "<%s>: %s" (geiser-con--request-id req) str)
+          (comint-redirect-send-command (format "%s" str) rbuffer nil t))))))
 
 (defun geiser-con--process-completed-request (req)
-  (let ((cont (geiser-con--request-continuation req))
-        (id (geiser-con--request-id req))
-        (rstr (geiser-con--request-string req))
-        (buffer (geiser-con--request-buffer req)))
+  (let* ((cont (geiser-con--request-continuation req))
+         (id (geiser-con--request-id req))
+         (rstr (geiser-con--request-string req))
+         (buffer (geiser-con--request-buffer req))
+         (con (geiser-con--request-connection req))
+         (form (geiser-con--comint-buffer-form con)))
     (if (not cont)
-        (geiser-log--warn "<%s> Droping result for request %S (%s)"
-                          id rstr req)
+        (geiser-log--warn "<%s> Droping result for request %S: %s"
+                          id rstr form)
       (condition-case cerr
           (with-current-buffer (or buffer (current-buffer))
-            (funcall cont (geiser-con--comint-buffer-form))
+            (funcall cont form)
+            (geiser-con--request-deactivate req)
             (geiser-log--info "<%s>: processed" id))
         (error (geiser-log--error
-                "<%s>: continuation failed %S \n\t%s" id rstr cerr))))))
+                "<%s>: continuation failed %S \n\t%s" id rstr cerr))))
+    (geiser-con--connection-clean-current-request con)))
 
 (defun geiser-con--comint-redirect-hook ()
   (if (not geiser-con--connection)
       (geiser-log--error "No connection in buffer")
     (let ((req (geiser-con--connection-current-request
                 geiser-con--connection)))
-      (if (not req) (geiser-log--error "No current request")
-        (geiser-con--process-completed-request req)
-        (geiser-con--connection-clean-current-request
-         geiser-con--connection)))))
+      (if (not req)
+          (geiser-log--error "No current request")
+        (geiser-con--process-completed-request req)))))
 
 (defadvice comint-redirect-setup
   (after geiser-con--advice
          (output-buffer comint-buffer finished-regexp &optional echo))
   (with-current-buffer comint-buffer
+    (when geiser-con--eot-regexp
+      (setq comint-redirect-finished-regexp geiser-con--eot-regexp))
     (when geiser-con--connection (setq mode-line-process nil))))
 (ad-activate 'comint-redirect-setup)
 
@@ -259,43 +277,27 @@
 
 (defconst geiser-con--error-message "Geiser connection not active")
 
-(defun geiser-con--send-string (buffer/proc str cont &optional sender-buffer)
-  (save-current-buffer
-    (let ((con (geiser-con--get-connection buffer/proc)))
-      (unless con (error geiser-con--error-message))
-      (let ((req (geiser-con--make-request str cont sender-buffer)))
-        (geiser-con--connection-add-request con req)
-        (geiser-con--process-next con)
-        req))))
-
 (defvar geiser-connection-timeout 30000
   "Time limit, in msecs, blocking on synchronous evaluation requests")
 
-(defun geiser-con--send-string/wait (buffer/proc str cont
-                                     &optional timeout sbuf)
+(defun geiser-con--send-string/wait (b/p str cont &optional timeout sbuf)
   (save-current-buffer
-    (let ((con (geiser-con--get-connection buffer/proc)))
-      (unless (geiser-con--connection-process con)
-        (error geiser-con--error-message))
-      (with-current-buffer (geiser-con--connection-buffer con)
-        (when (geiser-con--is-debugging)
-          (error "Geiser REPL is in debug mode")))
-      (let* ((req (geiser-con--send-string buffer/proc str cont sbuf))
-             (id (and req (geiser-con--request-id req)))
-             (time (or timeout geiser-connection-timeout))
-             (step 100)
-             (waitsecs (/ step 1000.0)))
-        (when id
+    (let* ((con (geiser-con--get-connection b/p))
+           (proc (and con (geiser-con--connection-process con))))
+      (unless proc (error geiser-con--error-message))
+      (when (geiser-con--is-debugging con) (error "REPL is in debug mode"))
+      (let* ((req (geiser-con--make-request con str cont sbuf))
+             (id (geiser-con--request-id req))
+             (timeout (/ (or timeout geiser-connection-timeout) 1000.0))
+             (waitsecs 0.1))
+        (geiser-con--connection-add-request con req)
+        (with-timeout (timeout (geiser-con--request-deactivate req))
           (condition-case nil
-              (while (and (> time 0)
-                          (geiser-con--connection-process con)
+              (while (and (geiser-con--connection-process con)
                           (not (geiser-con--connection-completed-p con id)))
-                (accept-process-output nil waitsecs)
-                (setq time (- time step)))
-            (error (setq time 0)))
-          (or (> time 0)
-              (geiser-con--request-deactivate req)
-              nil))))))
+                (geiser-con--process-next con)
+                (accept-process-output proc waitsecs nil t))
+            (error (geiser-con--request-deactivate req))))))))
 
 
 (provide 'geiser-connection)
diff --git a/elisp/geiser-eval.el b/elisp/geiser-eval.el
index df31594..3534312 100644
--- a/elisp/geiser-eval.el
+++ b/elisp/geiser-eval.el
@@ -113,6 +113,7 @@ module-exports, autodoc, callers, callees and generic-methods.")
                           (mapconcat 'geiser-eval--scheme-str code " ")
                           ")"))))
         ((symbolp code) (format "%s" code))
+        ((stringp code) (format "%S" (substring-no-properties code)))
         (t (format "%S" code))))
 
 
@@ -135,12 +136,6 @@ module-exports, autodoc, callers, callees and generic-methods.")
 (defun geiser-eval--set-sync-retort (s)
   (setq geiser-eval--sync-retort (geiser-eval--log s)))
 
-(defsubst geiser-eval--send (code cont &optional buffer)
-  (geiser-con--send-string (geiser-eval--proc)
-                           (geiser-eval--code-str code)
-                           `(lambda (s) (,cont (geiser-eval--log s)))
-                           buffer))
-
 (defun geiser-eval--send/wait (code &optional timeout buffer)
   (setq geiser-eval--sync-retort nil)
   (geiser-con--send-string/wait (geiser-eval--proc)
diff --git a/elisp/geiser-guile.el b/elisp/geiser-guile.el
index 93d1237..f410674 100644
--- a/elisp/geiser-guile.el
+++ b/elisp/geiser-guile.el
@@ -144,8 +144,9 @@ This function uses `geiser-guile-init-file' if it exists."
              :f)))
         ((listp module) module)
         ((stringp module)
-         (or (ignore-errors (car (geiser-syntax--read-from-string module)))
-             :f))
+         (condition-case nil
+             (car (geiser-syntax--read-from-string module))
+           (error :f)))
         (t :f)))
 
 (defun geiser-guile--module-cmd (module fmt &optional def)
@@ -198,10 +199,14 @@ This function uses `geiser-guile-init-file' if it exists."
 
 ;;; Trying to ascertain whether a buffer is Guile Scheme:
 
+(defconst geiser-guile--guess-re
+  (format "\\(%s\\|#! *.+\\(/\\| \\)guile\\( *\\\\\\)?\\)"
+          geiser-guile--module-re))
+
 (defun geiser-guile--guess ()
   (save-excursion
     (goto-char (point-min))
-    (re-search-forward geiser-guile--module-re nil t)))
+    (re-search-forward geiser-guile--guess-re nil t)))
 
 
 ;;; Compilation shell regexps
diff --git a/elisp/geiser-mode.el b/elisp/geiser-mode.el
index e9e5563..719176d 100644
--- a/elisp/geiser-mode.el
+++ b/elisp/geiser-mode.el
@@ -176,6 +176,35 @@ With prefix, try to enter the current's buffer module."
     (goto-char (point-max))
     (pop-to-buffer b)))
 
+(defun geiser-squarify (n)
+  "Toggle between () and [] for current form.
+With numeric prefix, perform that many toggles, forward for
+positive values and backward for negative."
+  (interactive "p")
+  (let ((pared (and (boundp 'paredit-mode) paredit-mode))
+        (fwd (> n 0))
+        (steps (abs n)))
+    (when (and pared (fboundp 'paredit-mode)) (paredit-mode -1))
+    (unwind-protect
+        (save-excursion
+          (unless (looking-at-p "\\s(") (backward-up-list))
+          (while (> steps 0)
+            (let ((p (point))
+                  (round (looking-at-p "(")))
+              (forward-sexp)
+              (backward-delete-char 1)
+              (insert (if round "]" ")"))
+              (goto-char p)
+              (delete-char 1)
+              (insert (if round "[" "("))
+              (setq steps (1- steps))
+              (backward-char)
+              (condition-case nil
+                  (progn (when fwd (forward-sexp 2))
+                         (backward-sexp))
+                (error (setq steps 0))))))
+      (when (and pared (fboundp 'paredit-mode)) (paredit-mode 1)))))
+
 
 ;;; Geiser mode:
 
@@ -258,6 +287,7 @@ interacting with the Geiser REPL is at your disposal.
   ("Complete module name" ((kbd "M-`") (kbd "C-."))
    geiser-completion--complete-module)
   ("Edit module" ("\C-c\C-e\C-m" "\C-c\C-em") geiser-edit-module)
+  ("Toggle ()/[]" ("\C-c\C-e\C-[" "\C-c\C-e[") geiser-squarify)
   --
   ("Callers" ((kbd "C-c <")) geiser-xref-callers
    :enable (and (geiser-eval--supported-p 'callers) (symbol-at-point)))
diff --git a/elisp/geiser-racket.el b/elisp/geiser-racket.el
index c32bcc9..8c66e67 100644
--- a/elisp/geiser-racket.el
+++ b/elisp/geiser-racket.el
@@ -150,7 +150,8 @@ This function uses `geiser-racket-init-file' if it exists."
        (format "(require %s)" module)))
 
 (defun geiser-racket--exit-command ()
-  (not (geiser-eval--send/result '(:eval (exit) geiser/emacs))))
+  (comint-send-eof)
+  (get-buffer-process (current-buffer)))
 
 (defconst geiser-racket--binding-forms
   '(for for/list for/hash for/hasheq for/and for/or
@@ -168,7 +169,7 @@ This function uses `geiser-racket-init-file' if it exists."
 
 (defsubst geiser-racket--get-help (symbol module)
   (geiser-eval--send/wait
-   `(:eval (get-help ',symbol (:module ,module)) geiser/autodoc)))
+   `(:eval (get-help ',symbol '(:module ,module)) geiser/autodoc)))
 
 (defun geiser-racket--external-help (id module)
   (message "Requesting help for '%s'..." id)
@@ -222,6 +223,18 @@ This function uses `geiser-racket-init-file' if it exists."
       (geiser-racket--explicit-module)))
 
 
+;;; Remote REPLs
+
+(defun connect-to-racket ()
+  "Start a Racket REPL connected to a remote process.
+
+The remote process needs to be running a REPL server started
+using start-geiser, a procedure in the geiser/server module."
+  (interactive)
+  (geiser-connect 'racket))
+
+
+
 ;;; Implementation definition:
 
 (define-geiser-implementation racket
@@ -229,6 +242,7 @@ This function uses `geiser-racket-init-file' if it exists."
   (binary geiser-racket--binary)
   (arglist geiser-racket--parameters)
   (startup)
+  (eot-regexp "\0")
   (prompt-regexp geiser-racket--prompt-regexp)
   (marshall-procedure geiser-racket--geiser-procedure)
   (find-module geiser-racket--get-module)
diff --git a/elisp/geiser-repl.el b/elisp/geiser-repl.el
index 57111f4..a05346c 100644
--- a/elisp/geiser-repl.el
+++ b/elisp/geiser-repl.el
@@ -156,9 +156,10 @@ expression, if any."
       (pop-to-buffer
        (or old
            (generate-new-buffer (format "* %s *"
-                                        (geiser-repl--repl-name impl)))))))
-  (geiser-repl-mode)
-  (geiser-impl--set-buffer-implementation impl))
+                                        (geiser-repl--repl-name impl)))))
+      (unless old
+        (geiser-repl-mode)
+        (geiser-impl--set-buffer-implementation impl)))))
 
 (geiser-impl--define-caller geiser-repl--binary binary ()
   "A variable or function returning the path to the scheme binary
@@ -205,23 +206,25 @@ module command as a string")
 (defsubst geiser-repl--port () (cdr geiser-repl--address))
 (defsubst geiser-repl--remote-p () geiser-repl--address)
 
-(defun geiser-repl--get-address ()
+(defun geiser-repl--get-address (&optional host port)
   (let ((defhost (or (geiser-repl--host) geiser-repl-default-host))
         (defport (or (geiser-repl--port) geiser-repl-default-port)))
-    (cons (read-string (format "Host (default %s): " defhost) nil nil defhost)
-          (read-number "Port: " defport))))
+    (cons (or host
+              (read-string (format "Host (default %s): " defhost)
+                           nil nil defhost))
+          (or port (read-number "Port: " defport)))))
 
 (defun geiser-repl--save-remote-data (remote address)
   (setq geiser-repl--address (and remote address))
-  (when remote
-    (setq header-line-format (format "Host: %s   Port: %s"
-                                     (geiser-repl--host)
-                                     (geiser-repl--port)))))
+  (setq header-line-format (and remote
+                                (format "Host: %s   Port: %s"
+                                        (geiser-repl--host)
+                                        (geiser-repl--port)))))
 
-(defun geiser-repl--start-repl (impl &optional remote)
+(defun geiser-repl--start-repl (impl &optional remote host port)
   (message "Starting Geiser REPL for %s ..." impl)
   (geiser-repl--to-repl-buffer impl)
-  (let ((program (if remote (geiser-repl--get-address)
+  (let ((program (if remote (geiser-repl--get-address host port)
                    (geiser-repl--binary impl)))
         (args (geiser-repl--arglist impl))
         (prompt-rx (geiser-repl--prompt-regexp impl))
@@ -246,7 +249,8 @@ module command as a string")
                                   deb-preamble-rx)
     (add-to-list 'geiser-repl--repls (current-buffer))
     (geiser-repl--set-this-buffer-repl (current-buffer))
-    (geiser-repl--startup impl)))
+    (geiser-repl--startup impl)
+    (message "Geiser REPL up and running!")))
 
 (defun geiser-repl--process ()
   (let ((buffer (geiser-repl--set-up-repl geiser-impl--implementation)))
@@ -287,7 +291,7 @@ module command as a string")
               "Start Geiser for scheme implementation: "))))
    (geiser-repl--start-repl impl))
 
-(defun geiser-connect (impl)
+(defun geiser-connect (impl &optional host port)
   "Start a new Geiser REPL connected to a remote Scheme process."
   (interactive
    (list (or (geiser-repl--only-impl-p)
@@ -295,7 +299,7 @@ module command as a string")
                   geiser-impl--implementation)
              (geiser-repl--read-impl
               "Scheme implementation: "))))
-  (geiser-repl--start-repl impl t))
+  (geiser-repl--start-repl impl t host port))
 
 (make-variable-buffer-local
  (defvar geiser-repl--last-scm-buffer nil))
@@ -306,14 +310,21 @@ With prefix argument, ask for which one if more than one is running.
 If no REPL is running, execute `run-geiser' to start a fresh one."
   (interactive "P")
   (let* ((impl (or impl geiser-impl--implementation))
-         (repl (cond ((and (not ask) (not impl)
+         (in-repl (eq major-mode 'geiser-repl-mode))
+         (in-live-repl (and in-repl (get-buffer-process (current-buffer))))
+         (repl (cond ((and (not ask)
+                           (not impl)
+                           (not in-repl)
                            (or geiser-repl--repl (car geiser-repl--repls))))
-                     ((and (not ask) impl (geiser-repl--repl/impl impl)))))
+                     ((and (not ask)
+                           (not in-repl)
+                           impl
+                           (geiser-repl--repl/impl impl)))))
          (pop-up-windows geiser-repl-window-allow-split))
-    (cond ((and (eq (current-buffer) repl)
-                (not (eq repl buffer))
-                (buffer-live-p geiser-repl--last-scm-buffer))
-           (pop-to-buffer geiser-repl--last-scm-buffer))
+    (cond ((or in-live-repl
+               (and (eq (current-buffer) repl) (not (eq repl buffer))))
+           (when (buffer-live-p geiser-repl--last-scm-buffer)
+             (pop-to-buffer geiser-repl--last-scm-buffer)))
           (repl (pop-to-buffer repl))
           ((geiser-repl--remote-p) (geiser-connect impl))
           (t (run-geiser impl)))
@@ -334,7 +345,8 @@ If no REPL is running, execute `run-geiser' to start a fresh one."
   "Switch to running Geiser REPL and try to enter a given module."
   (interactive)
   (let* ((module (or module
-                     (geiser-completion--read-module "Switch to module: ")))
+                     (geiser-completion--read-module
+                      "Switch to module (default top-level): ")))
          (cmd (and module
                    (geiser-repl--enter-cmd geiser-impl--implementation
                                            module))))
@@ -505,11 +517,19 @@ With a prefix argument, force exit by killing the scheme process."
                (insert "\n"))))))
 
 (defun geiser-repl--tab (n)
+  "If we're after the last prompt, complete symbol or indent (if
+there's no symbol at point). Otherwise, go to next error in the REPL
+buffer."
   (interactive "p")
   (if (> (point) (geiser-repl--last-prompt-end))
       (geiser-completion--maybe-complete)
     (compilation-next-error n)))
 
+(defun geiser-repl--previous-error (n)
+  "Go to previous error in the REPL buffer."
+  (interactive "p")
+  (compilation-next-error (- n)))
+
 (define-derived-mode geiser-repl-mode comint-mode "REPL"
   "Major mode for interacting with an inferior scheme repl process.
 \\{geiser-repl-mode-map}"
@@ -535,13 +555,14 @@ With a prefix argument, force exit by killing the scheme process."
 (define-key geiser-repl-mode-map [return] 'geiser-repl--maybe-send)
 (define-key geiser-repl-mode-map "\C-j" 'geiser-repl--newline-and-indent)
 (define-key geiser-repl-mode-map (kbd "TAB") 'geiser-repl--tab)
+(define-key geiser-repl-mode-map [backtab] 'geiser-repl--previous-error)
 
 (define-key geiser-repl-mode-map "\C-a" 'geiser-repl--bol)
 (define-key geiser-repl-mode-map (kbd "<home>") 'geiser-repl--bol)
 
 (geiser-menu--defmenu repl geiser-repl-mode-map
-  ("Complete symbol" ((kbd "TAB") (kbd "M-TAB"))
-   geiser-completion--complete-symbol :enable (symbol-at-point))
+  ("Complete symbol" ((kbd "M-TAB"))
+   geiser-repl--tab :enable (symbol-at-point))
   ("Complete module name" ((kbd "C-.") (kbd "M-`"))
    geiser-completion--complete-module :enable (symbol-at-point))
   ("Edit symbol" "\M-." geiser-edit-symbol-at-point