branch: externals/dash
commit 6d8abc7322ab4509f5836c05b8145090d725fb19
Author: Mika Vilpas <mika.vil...@gmail.com>
Commit: Matus Goljer <dota.k...@gmail.com>
Add -doto macro (like Clojure's doto) (#177)
* Add -doto macro (like Clojure's doto)
Here is its documentation in clojuredocs:
(doto x & forms)
Evaluates x then calls all of the methods and functions with the
value of x supplied at the front of the given arguments. The forms
are evaluated in order. Returns x.
(doto (new java.util.HashMap) (.put "a" 1) (.put "b" 2))
Documentation:
https://clojuredocs.org/clojure.core/doto
Source (clojure):
https://github.com/clojure/clojure/blob/clojure-1.7.0/src/clj/clojure/core.clj#L3700
* Use make-symbol instead of gensym to stay consistent
Consistent with other code in dash.el
* Fix referring to rest from cl.el in -doto
* Add doto example with setcar and setcdr
* Clarify -doto docstring: eval-initial-value evalled only once
Also mention all arguments in the docstring to please checkdoc
* Make -doto documentation more in line with Emacs standards
---
dash.el | 15 +++++++++++++++
dev/examples.el | 6 +++++-
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/dash.el b/dash.el
index 41651a1..8938674 100644
--- a/dash.el
+++ b/dash.el
@@ -71,6 +71,21 @@ special values."
(setq it-index (1+ it-index))
(!cdr ,l)))))
+(defmacro -doto (eval-initial-value &rest forms)
+ "Eval a form, then insert that form as the 2nd argument to other forms.
+The EVAL-INITIAL-VALUE form is evaluated once. Its result is
+passed to FORMS, which are then evaluated sequentially. Returns
+the target form."
+ (declare (indent 1))
+ (let ((retval (make-symbol "value")))
+ `(let ((,retval ,eval-initial-value))
+ ,@(mapcar (lambda (form)
+ (if (sequencep form)
+ `(,(-first-item form) ,retval ,@(cdr form))
+ `(funcall form ,retval)))
+ forms)
+ ,retval)))
+
(defun -each (list fn)
"Call FN with every item in LIST. Return nil, used for side-effects only."
(--each list (funcall fn it)))
diff --git a/dev/examples.el b/dev/examples.el
index 92f8861..ade7eab 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -1020,7 +1020,11 @@ new list."
(defexamples -dotimes
(let (s) (-dotimes 3 (lambda (n) (!cons n s))) s) => '(2 1 0)
- (let (s) (--dotimes 5 (!cons it s)) s) => '(4 3 2 1 0)))
+ (let (s) (--dotimes 5 (!cons it s)) s) => '(4 3 2 1 0))
+
+ (defexamples -doto
+ (-doto '(1 2 3) (!cdr) (!cdr)) => '(3)
+ (-doto '(1 . 2) (setcar 3) (setcdr 4)) => '(3 . 4)))
(def-example-group "Destructive operations" nil
(defexamples !cons
