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[Emacs-diffs] master 0f443a1: New library thunk.el
From: |
Nicolas Petton |
Subject: |
[Emacs-diffs] master 0f443a1: New library thunk.el |
Date: |
Fri, 23 Oct 2015 11:22:25 +0000 |
branch: master
commit 0f443a12368d02e256c7e94c3de574c6ceaed86e
Author: Nicolas Petton <address@hidden>
Commit: Nicolas Petton <address@hidden>
New library thunk.el
thunk.el is extracted from stream.el in ELPA, with additional tests.
* lisp/emacs-lisp/thunk.el: New file.
* test/automated/thunk-tests.el: New file.
* etc/NEWS: Add information about thunk.el
---
etc/NEWS | 5 +++
lisp/emacs-lisp/thunk.el | 63 +++++++++++++++++++++++++++++++++++++++++
test/automated/thunk-tests.el | 55 +++++++++++++++++++++++++++++++++++
3 files changed, 123 insertions(+), 0 deletions(-)
diff --git a/etc/NEWS b/etc/NEWS
index 6588aad..58ab6be 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -582,6 +582,11 @@ prefixed with `seq-' and work on lists, strings and
vectors.
The map library provides map-manipulation functions that work on alists,
hash-table and arrays. All functions are prefixed with "map-".
+** thunk
+*** New thunk library:
+Thunk provides functions and macros to control the evaluation of
+forms.
+
** Calendar and diary
+++
diff --git a/lisp/emacs-lisp/thunk.el b/lisp/emacs-lisp/thunk.el
new file mode 100644
index 0000000..ab366d2
--- /dev/null
+++ b/lisp/emacs-lisp/thunk.el
@@ -0,0 +1,63 @@
+;;; thunk.el --- Lazy form evaluation -*- lexical-binding: t -*-
+
+;; Copyright (C) 2015 Free Software Foundation, Inc.
+
+;; Author: Nicolas Petton <address@hidden>
+;; Keywords: sequences
+;; Version: 1.0
+;; Package: thunk
+
+;; Maintainer: address@hidden
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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 Emacs 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 GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; Thunk provides functions and macros to control the evaluation of
+;; forms. Use `thunk-delay' to delay the evaluation of a form, and
+;; `thunk-force' to evaluate it. Evaluation is cached, and only
+;; happens once.
+
+;; Tests are located at test/automated/thunk-tests.el
+
+;;; Code:
+
+(defmacro thunk-delay (&rest body)
+ "Delay the evaluation of BODY."
+ (declare (debug t))
+ (let ((forced (make-symbol "forced"))
+ (val (make-symbol "val")))
+ `(let (,forced ,val)
+ (lambda (&optional check)
+ (if check
+ ,forced
+ (unless ,forced
+ (setf ,val (progn ,@body))
+ (setf ,forced t)))
+ ,val))))
+
+(defun thunk-force (delayed)
+ "Force the evaluation of DELAYED.
+The result is cached and will be returned on subsequent calls
+with the same DELAYED argument."
+ (funcall delayed))
+
+(defun thunk-evaluated-p (delayed)
+ "Return non-nil if DELAYED has been evaluated."
+ (funcall delayed t))
+
+(provide 'thunk)
+;;; thunk.el ends here
diff --git a/test/automated/thunk-tests.el b/test/automated/thunk-tests.el
new file mode 100644
index 0000000..7abbd29
--- /dev/null
+++ b/test/automated/thunk-tests.el
@@ -0,0 +1,55 @@
+;;; thunk-tests.el --- Tests for thunk.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2015 Free Software Foundation, Inc.
+
+;; Author: Nicolas Petton <address@hidden>
+;; Maintainer: address@hidden
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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 Emacs 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 GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Tests for thunk.el
+
+;;; Code:
+
+(require 'ert)
+(require 'thunk)
+
+(ert-deftest thunk-should-be-lazy ()
+ (let (x)
+ (thunk-delay (setq x t))
+ (should (null x))))
+
+(ert-deftest thunk-can-be-evaluated ()
+ (let* (x
+ (thunk (thunk-delay (setq x t))))
+ (should-not (thunk-evaluated-p thunk))
+ (should (null x))
+ (thunk-force thunk)
+ (should (thunk-evaluated-p thunk))
+ (should x)))
+
+(ert-deftest thunk-evaluation-is-cached ()
+ (let* ((x 0)
+ (thunk (thunk-delay (setq x (1+ x)))))
+ (thunk-force thunk)
+ (should (= x 1))
+ (thunk-force thunk)
+ (should (= x 1))))
+
+(provide 'thunk-tests)
+;;; thunk-tests.el ends here
- [Emacs-diffs] master 0f443a1: New library thunk.el,
Nicolas Petton <=