branch: externals/dash
commit c62dfb0b77c6552a2534985ecb1cebb8b783076d
Author: Basil L. Contovounesios <conto...@tcd.ie>
Commit: Basil L. Contovounesios <conto...@tcd.ie>
Fix -pad when fed zero input lists
* NEWS.md (2.20.0): Mention fix.
* README.md:
* dash.texi: Regenerate docs.
* dash.el (-pad): Don't barf on zero input lists. Fix docstring.
Mark as pure and side-effect-free. Simplify.
* dev/examples.el (-pad): Extend tests.
---
NEWS.md | 1 +
README.md | 11 +++++++----
dash.el | 14 +++++++++-----
dash.texi | 15 +++++++++------
dev/examples.el | 11 +++++++++--
5 files changed, 35 insertions(+), 17 deletions(-)
diff --git a/NEWS.md b/NEWS.md
index 6d2553f7c7..ab08c1ee76 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -12,6 +12,7 @@ See the end of the file for license conditions.
- Fixed a regression from `2.18` in `-take` that caused it to
prematurely signal an error on improper lists (#393).
+- The function `-pad` can now be called with zero lists as arguments.
- The functions `-union`, `-intersection`, and `-difference` now
return proper sets, without duplicate elements (#397).
- The functions `-same-items?` and `-permutations` now work on
diff --git a/README.md b/README.md
index f98ae44829..64789b69d1 100644
--- a/README.md
+++ b/README.md
@@ -2063,13 +2063,16 @@ from the beginning.
#### -pad `(fill-value &rest lists)`
-Appends `fill-value` to the end of each list in `lists` such that they
-will all have the same length.
+Pad each of `lists` with `fill-value` until they all have equal lengths.
+
+Ensure all `lists` are as long as the longest one by repeatedly
+appending `fill-value` to the shorter lists, and return the
+resulting `lists`.
```el
(-pad 0 ()) ;; => (nil)
-(-pad 0 '(1)) ;; => ((1))
-(-pad 0 '(1 2 3) '(4 5)) ;; => ((1 2 3) (4 5 0))
+(-pad 0 '(1 2) '(3 4)) ;; => ((1 2) (3 4))
+(-pad 0 '(1 2) '(3 4 5 6) '(7 8 9)) ;; => ((1 2 0 0) (3 4 5 6) (7 8 9 0))
```
#### -table `(fn &rest lists)`
diff --git a/dash.el b/dash.el
index 04c3ca1d5e..ed3a15131f 100644
--- a/dash.el
+++ b/dash.el
@@ -1704,11 +1704,15 @@ from the beginning."
(nconc newlist newlist)))
(defun -pad (fill-value &rest lists)
- "Appends FILL-VALUE to the end of each list in LISTS such that they
-will all have the same length."
- (let* ((annotations (-annotate 'length lists))
- (n (-max (-map 'car annotations))))
- (--map (append (cdr it) (-repeat (- n (car it)) fill-value)) annotations)))
+ "Pad each of LISTS with FILL-VALUE until they all have equal lengths.
+
+Ensure all LISTS are as long as the longest one by repeatedly
+appending FILL-VALUE to the shorter lists, and return the
+resulting LISTS."
+ (declare (pure t) (side-effect-free t))
+ (let* ((lens (mapcar #'length lists))
+ (maxlen (apply #'max 0 lens)))
+ (--map (append it (make-list (- maxlen (pop lens)) fill-value)) lists)))
(defun -annotate (fn list)
"Return a list of cons cells where each cell is FN applied to each
diff --git a/dash.texi b/dash.texi
index 9f2f05a5c4..a38f20fd3a 100644
--- a/dash.texi
+++ b/dash.texi
@@ -3048,8 +3048,11 @@ from the beginning.
@anchor{-pad}
@defun -pad (fill-value &rest lists)
-Appends @var{fill-value} to the end of each list in @var{lists} such that they
-will all have the same length.
+Pad each of @var{lists} with @var{fill-value} until they all have equal
lengths.
+
+Ensure all @var{lists} are as long as the longest one by repeatedly
+appending @var{fill-value} to the shorter lists, and return the
+resulting @var{lists}.
@example
@group
@@ -3057,12 +3060,12 @@ will all have the same length.
@result{} (nil)
@end group
@group
-(-pad 0 '(1))
- @result{} ((1))
+(-pad 0 '(1 2) '(3 4))
+ @result{} ((1 2) (3 4))
@end group
@group
-(-pad 0 '(1 2 3) '(4 5))
- @result{} ((1 2 3) (4 5 0))
+(-pad 0 '(1 2) '(3 4 5 6) '(7 8 9))
+ @result{} ((1 2 0 0) (3 4 5 6) (7 8 9 0))
@end group
@end example
@end defun
diff --git a/dev/examples.el b/dev/examples.el
index d858e203ce..0b1ff173c5 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -1470,10 +1470,17 @@ related predicates."
(defexamples -pad
(-pad 0 '()) => '(())
+ (-pad 0 '(1 2) '(3 4)) => '((1 2) (3 4))
+ (-pad 0 '(1 2) '(3 4 5 6) '(7 8 9)) => '((1 2 0 0) (3 4 5 6) (7 8 9 0))
+ (-pad 0) => ()
+ (-pad 0 () ()) => '(() ())
(-pad 0 '(1)) => '((1))
+ (-pad 0 '(1) '(1)) => '((1) (1))
(-pad 0 '(1 2 3) '(4 5)) => '((1 2 3) (4 5 0))
- (-pad nil '(1 2 3) '(4 5) '(6 7 8 9 10)) => '((1 2 3 nil nil) (4 5 nil nil
nil) (6 7 8 9 10))
- (-pad 0 '(1 2) '(3 4)) => '((1 2) (3 4)))
+ (-pad nil ()) => '(())
+ (-pad nil () ()) => '(() ())
+ (-pad nil '(nil nil) '(nil) '(nil nil nil nil nil))
+ => '((nil nil nil nil nil) (nil nil nil nil nil) (nil nil nil nil nil)))
(defexamples -table
(-table '* '(1 2 3) '(1 2 3)) => '((1 2 3) (2 4 6) (3 6 9))
