On Tuesday, 24 May 2016 at 12:22:01 UTC, H. S. Teoh wrote:
And why would you assume that it would rotate right? The
default assumption, unless stated clearly and widely followed
everywhere, is unclear and leads to misunderstandings. I'd
rather unambiguously name them rotateRight and rotateLeft than
the asymmetric rotate / rotateLeft.
In the APL family, we have dyadic ⌽ and ⊖:
3⌽⍳9 ⍝ left
4 5 6 7 8 9 1 2 3
¯3⌽⍳9 ⍝ right
7 8 9 1 2 3 4 5 6
3 3⍴⍳9
1 2 3
4 5 6
7 8 9
1⊖3 3⍴⍳9 ⍝ up
4 5 6
7 8 9
1 2 3
¯1⊖3 3⍴⍳9 ⍝ down
7 8 9
1 2 3
4 5 6
They rotate left and up in the positive case because that yields
the natural indexing order. Right rotation gives you a reverse
ordering.
-Wyatt
