[elpa] externals/dash 0b9cdba 2/2: Speed up -flatten-n a bit

[ELPA Syncer]

branch: externals/dash
commit 0b9cdbaa31c7ae2406722fd9c534aad8f38fa1d5
Author: Basil L. Contovounesios <contovob@tcd.ie>
Commit: Basil L. Contovounesios <contovob@tcd.ie>

    Speed up -flatten-n a bit
    
    * dash.el (-flatten-n): Don't maintain a list of intermediate
    results.  Eta-reduce.
    * dev/examples.el (-flatten-n): Check for destructive side effects.
    
    Re: #373.
---
 dash.el         | 4 +++-
 dev/examples.el | 5 ++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/dash.el b/dash.el
index 9187c66..86f37c3 100644
--- a/dash.el
+++ b/dash.el
@@ -727,7 +727,9 @@ See also: `-flatten-n'"
 
 See also: `-flatten'"
   (declare (pure t) (side-effect-free t))
-  (-last-item (--iterate (--mapcat (-list it) it) list (1+ num))))
+  (dotimes (_ num)
+    (setq list (apply #'append (mapcar #'-list list))))
+  list)
 
 (defun -concat (&rest lists)
   "Return a new list with the concatenation of the elements in the supplied 
LISTS."
diff --git a/dev/examples.el b/dev/examples.el
index a0b115f..6997d89 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -344,7 +344,10 @@ new list."
     (-flatten-n 0 '(3 4)) => '(3 4)
     (-flatten-n 0 '((1 2) (3 4))) => '((1 2) (3 4))
     (-flatten-n 0 '(((1 2) (3 4)))) => '(((1 2) (3 4)))
-    (-flatten-n 1 '(((1 . 2)) ((3 . 4)))) => '((1 . 2) (3 . 4)))
+    (-flatten-n 1 '(((1 . 2)) ((3 . 4)))) => '((1 . 2) (3 . 4))
+    (let ((l (list 1 (list 2) 3))) (-flatten-n 0 l) l) => '(1 (2) 3)
+    (let ((l (list 1 (list 2) 3))) (-flatten-n 1 l) l) => '(1 (2) 3)
+    (let ((l (list 1 (list 2) 3))) (-flatten-n 2 l) l) => '(1 (2) 3))
 
   (defexamples -replace
     (-replace 1 "1" '(1 2 3 4 3 2 1)) => '("1" 2 3 4 3 2 "1")