Scheme version checks

And, if you happen to be launching it all the time, a way of skipping
them via a customizable variable.

Should address issue #15.

4 files changed, 50 insertions, 2 deletions

diff --git a/elisp/geiser-base.el b/elisp/geiser-base.el
index 2569034..e564b0f 100644
--- a/elisp/geiser-base.el
+++ b/elisp/geiser-base.el
@@ -1,6 +1,6 @@
 ;;; geiser-base.el --- shared bits
 
-;; Copyright (C) 2009, 2010, 2012  Jose Antonio Ortega Ruiz
+;; Copyright (C) 2009, 2010, 2012, 2013  Jose Antonio Ortega Ruiz
 
 ;; This program is free software; you can redistribute it and/or
 ;; modify it under the terms of the Modified BSD License. You should
@@ -74,5 +74,14 @@
   (let ((thing (thing-at-point 'symbol)))
     (and thing (make-symbol thing))))
 
+(defun geiser--cut-version (v)
+  (when (string-match "\\([0-9]+\\.[0-9]\\(?:\\.[0-9]+\\)?\\).*" v)
+    (match-string 1 v)))
+
+(defun geiser--version< (v1 v2)
+  (let ((v1 (geiser--cut-version v1))
+        (v2 (geiser--cut-version v2)))
+    (and v1 v2 (version< v1 v2))))
+
 
 (provide 'geiser-base)
diff --git a/elisp/geiser-guile.el b/elisp/geiser-guile.el
index 9182807..bc96973 100644
--- a/elisp/geiser-guile.el
+++ b/elisp/geiser-guile.el
@@ -289,6 +289,11 @@ This function uses `geiser-guile-init-file' if it exists."
 
 ;;; REPL startup
 
+(defconst geiser-guile-minimum-version "2.0")
+
+(defun geiser-guile--version (binary)
+  (shell-command-to-string (format "%s  -c '(display (version))'" binary)))
+
 (defun geiser-guile-update-warning-level ()
   "Update the warning level used by the REPL.
 The new level is set using the value of `geiser-guile-warning-level'."
@@ -364,6 +369,8 @@ it spawn a server thread."
 (define-geiser-implementation guile
   (binary geiser-guile--binary)
   (arglist geiser-guile--parameters)
+  (version-command geiser-guile--version)
+  (minimum-version geiser-guile-minimum-version)
   (repl-startup geiser-guile--startup)
   (prompt-regexp geiser-guile--prompt-regexp)
   (debugger-prompt-regexp geiser-guile--debugger-prompt-regexp)
diff --git a/elisp/geiser-racket.el b/elisp/geiser-racket.el
index 9b98945..59886e3 100644
--- a/elisp/geiser-racket.el
+++ b/elisp/geiser-racket.el
@@ -358,7 +358,12 @@ using start-geiser, a procedure in the geiser/server module."
  (with-handlers: 1))
 
 
-;;; Startup
+;;; REPL Startup
+
+(defvar geiser-racket-minimum-version "5.3")
+
+(defun geiser-racket--version (binary)
+  (shell-command-to-string (format "%s  -e '(display (version))'" binary)))
 
 (defun geiser-racket--startup (remote)
   (set (make-local-variable 'compilation-error-regexp-alist)
@@ -412,6 +417,8 @@ Use a prefix to be asked for a submodule name."
 (define-geiser-implementation racket
   (unsupported-procedures '(callers callees generic-methods))
   (binary geiser-racket--binary)
+  (minimum-version geiser-racket-minimum-version)
+  (version-command geiser-racket--version)
   (arglist geiser-racket--parameters)
   (repl-startup geiser-racket--startup)
   (prompt-regexp geiser-racket--prompt-regexp)
diff --git a/elisp/geiser-repl.el b/elisp/geiser-repl.el
index 68e4708..ebb74c2 100644
--- a/elisp/geiser-repl.el
+++ b/elisp/geiser-repl.el
@@ -105,6 +105,16 @@ expression, if any."
   :type 'boolean
   :group 'geiser-repl)
 
+(geiser-custom--defcustom geiser-repl-skip-version-check-p nil
+  "Whether to skip version checks for the Scheme executable.
+
+When set, Geiser won't check the version of the Scheme
+interpreter when starting a REPL, saving a few tenths of a
+second.
+"
+  :type 'boolean
+  :group 'geiser-repl)
+
 (geiser-custom--defcustom geiser-repl-query-on-exit-p nil
   "Whether to prompt for confirmation on \\[geiser-repl-exit]."
   :type 'boolean
@@ -188,6 +198,13 @@ module command as a string")
 (geiser-impl--define-caller geiser-repl--exit-cmd exit-command ()
   "Function returning the REPL exit command as a string")
 
+(geiser-impl--define-caller geiser-repl--version version-command (binary)
+  "Function returning the version of the corresponding scheme process,
+   given its full path.")
+
+(geiser-impl--define-caller geiser-repl--min-version minimum-version ()
+  "A variable providing the minimum required scheme version, as a string.")
+
 
 ;;; Geiser REPL buffers and processes:
 
@@ -355,6 +372,13 @@ module command as a string")
                                     geiser-repl-query-on-kill-p)
     (message "%s up and running!" (geiser-repl--repl-name impl))))
 
+(defun geiser-repl--check-version (impl)
+  (when (not geiser-repl-skip-version-check-p)
+    (let ((v (geiser-repl--version impl (geiser-repl--binary impl)))
+          (r (geiser-repl--min-version impl)))
+      (when (geiser--version< v r)
+        (error "Geiser requires %s version %s but detected %s" impl r v)))))
+
 (defun geiser-repl--start-scheme (impl address prompt)
   (setq comint-prompt-regexp prompt)
   (let* ((name (geiser-repl--repl-name impl))
@@ -363,6 +387,7 @@ module command as a string")
                  `(,(geiser-repl--binary impl)
                    nil
                    ,@(geiser-repl--arglist impl)))))
+    (when (not address) (geiser-repl--check-version impl))
     (condition-case err
         (apply 'make-comint-in-buffer `(,name ,buff ,@args))
       (error (insert "Unable to start REPL:\n"