emacs: Move code for evaluating to "guix-geiser.el".

* emacs/guix-backend.el: Adjust commentary. Move "eval" code to ...
  (guix-eval, guix-eval-read, guix-eval-in-repl): Adjust to use new
  functions.
* emacs/guix-geiser.el: ...here.  New file.
  (guix-geiser-eval, guix-geiser-eval-read, guix-geiser-eval-in-repl,
  guix-repl-send): New functions.
* emacs.am (ELFILES): Add "guix-geiser.el".

1 files changed, 84 insertions, 0 deletions

diff --git a/emacs/guix-geiser.el b/emacs/guix-geiser.el
new file mode 100644
index 0000000000..de139b72ff
--- /dev/null
+++ b/emacs/guix-geiser.el
@@ -0,0 +1,84 @@
+;;; guix-geiser.el --- Interacting with Geiser   -*- lexical-binding: t -*-
+
+;; Copyright © 2015 Alex Kost <alezost@gmail.com>
+
+;; This file is part of GNU Guix.
+
+;; GNU Guix 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 Guix 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This file provides functions to evaluate guile code using Geiser.
+
+;;; Code:
+
+(require 'geiser-mode)
+
+(defun guix-geiser-repl ()
+  "Return the current Geiser REPL."
+  (or geiser-repl--repl
+      (geiser-repl--repl/impl 'guile)
+      (error "Geiser REPL not found")))
+
+(defun guix-geiser-eval (str &optional repl)
+  "Evaluate STR with guile expression using Geiser REPL.
+If REPL is nil, use the current Geiser REPL.
+Return a list of strings with result values of evaluation."
+  (with-current-buffer (or repl (guix-geiser-repl))
+    (let ((res (geiser-eval--send/wait `(:eval (:scm ,str)))))
+      (if (geiser-eval--retort-error res)
+          (error "Error in evaluating guile expression: %s"
+                 (geiser-eval--retort-output res))
+        (cdr (assq 'result res))))))
+
+(defun guix-geiser-eval-read (str &optional repl)
+  "Evaluate STR with guile expression using Geiser REPL.
+Return elisp expression of the first result value of evaluation."
+  ;; Parsing scheme code with elisp `read' is probably not the best idea.
+  (read (replace-regexp-in-string
+         "#f\\|#<unspecified>" "nil"
+         (replace-regexp-in-string
+          "#t" "t" (car (guix-geiser-eval str repl))))))
+
+(defun guix-repl-send (cmd &optional save-history)
+  "Send CMD input string to the current REPL buffer.
+This is the same as `geiser-repl--send', but with SAVE-HISTORY
+argument.  If SAVE-HISTORY is non-nil, save CMD in the REPL
+history."
+  (when (and cmd (eq major-mode 'geiser-repl-mode))
+    (geiser-repl--prepare-send)
+    (goto-char (point-max))
+    (comint-kill-input)
+    (insert cmd)
+    (let ((comint-input-filter (if save-history
+                                   comint-input-filter
+                                 'ignore)))
+      (comint-send-input nil t))))
+
+(defun guix-geiser-eval-in-repl (str &optional repl no-history no-display)
+  "Switch to Geiser REPL and evaluate STR with guile expression there.
+If NO-HISTORY is non-nil, do not save STR in the REPL history.
+If NO-DISPLAY is non-nil, do not switch to the REPL buffer."
+  (let ((repl (or repl (guix-geiser-repl))))
+    (with-current-buffer repl
+      ;; XXX Since Geiser 0.8, `geiser-repl--send' has SAVE-HISTORY
+      ;; argument, so use this function eventually and remove
+      ;; `guix-repl-send'.
+      (guix-repl-send str (not no-history)))
+    (unless no-display
+      (geiser-repl--switch-to-buffer repl))))
+
+(provide 'guix-geiser)
+
+;;; guix-geiser.el ends here