New definitions -every and --every

* dash.el (--every, -every): New definitions; to --every-p and
-every-p what --some and -some are to --some-p and -some-p,
respectively.
(--any?): Open-code ---truthy? for clarity.
(--all?): Rewrite in terms of --every.  Extend docstring.
(-all?): Extend docstring.

* dev/examples.el (-any?, -all?, -some): Extend tests.
(-every): New tests.

* NEWS.md (2.19.0): Announce -every and --every.

* README.md:
* dash.texi: Regenerate docs.

NEWS.md

@@ -8,11 +8,19 @@ See the end of the file for license conditions.
 
 ### From 2.18.1 to 2.19.0
 
+#### Fixes
+
 - Reverted a breaking change introduced in `2.18.0` that caused the
   threading macro `-->` to be indented differently from `->` and
   `->>` (#375).
 - Added and fixed Edebug specifications for many Dash macros (Philipp
   Stephani, #380, #381).
+
+#### New features
+
+- New function `-every` and its anaphoric macro counterpart `--every`.
+  They are like the existing `-every-p` and `--every-p`, respectively,
+  but return the last non-`nil` result instead of just `t`.
 - New macro `--partition-after-pred` which affords
   `-partition-after-pred` better performance (Per Weijnitz, #362).
 

README.md

@@ -293,6 +293,7 @@ Other list functions not fit to be classified elsewhere.
 * [`-table-flat`](#-table-flat-fn-rest-lists) `(fn &rest lists)`
 * [`-first`](#-first-pred-list) `(pred list)`
 * [`-some`](#-some-pred-list) `(pred list)`
+* [`-every`](#-every-pred-list) `(pred list)`
 * [`-last`](#-last-pred-list) `(pred list)`
 * [`-first-item`](#-first-item-list) `(list)`
 * [`-second-item`](#-second-item-list) `(list)`
@@ -1275,20 +1276,28 @@ Return t if (`pred` x) is non-nil for any x in `list`, else nil.
 Alias: `-any-p`, `-some?`, `-some-p`
 
 ```el
-(-any? 'even? '(1 2 3)) ;; => t
+(-any? #'numberp '(nil 0 t)) ;; => t
-(-any? 'even? '(1 3 5)) ;; => nil
+(-any? #'numberp '(nil t t)) ;; => nil
-(-any? 'null '(1 3 5)) ;; => nil
+(-any? #'null '(1 3 5)) ;; => nil
 ```
 
 #### -all? `(pred list)`
 
-Return t if (`pred` x) is non-nil for all x in `list`, else nil.
+Return t if (`pred` `x`) is non-nil for all `x` in `list`, else nil.
+In the latter case, stop after the first `x` for which (`pred` `x`) is
+nil, without calling `pred` on any subsequent elements of `list`.
 
-Alias: `-all-p`, `-every?`, `-every-p`
+The similar function [`-every`](#-every-pred-list) is more widely useful, since it
+returns the last non-nil result of `pred` instead of just t on
+success.
+
+Alias: `-all-p`, `-every-p`, `-every?`.
+
+This function's anaphoric counterpart is `--all?`.
 
 ```el
-(-all? 'even? '(1 2 3)) ;; => nil
+(-all? #'numberp '(1 2 3)) ;; => t
-(-all? 'even? '(2 4 6)) ;; => t
+(-all? #'numberp '(2 t 6)) ;; => nil
 (--all? (= 0 (% it 2)) '(2 4 6)) ;; => t
 ```
 
@@ -2019,9 +2028,27 @@ Alias: `-any`.
 This function's anaphoric counterpart is `--some`.
 
 ```el
-(-some (lambda (s) (string-match-p "x" s)) '("foo" "axe" "xor")) ;; => 1
+(-some #'stringp '(1 "2" 3)) ;; => t
-(-some (lambda (s) (string-match-p "x" s)) '("foo" "bar" "baz")) ;; => nil
+(--some (string-match-p "x" it) '("foo" "axe" "xor")) ;; => 1
-(--some (member 'foo it) '((foo bar) (baz))) ;; => (foo bar)
+(--some (= it-index 3) '(0 1 2)) ;; => nil
+```
+
+#### -every `(pred list)`
+
+Return non-nil if `pred` returns non-nil for all items in `list`.
+If so, return the last such result of `pred`.  Otherwise, once an
+item is reached for which `pred` returns nil, return nil without
+calling `pred` on any further `list` elements.
+
+This function is like `-every-p`, but on success returns the last
+non-nil result of `pred` instead of just t.
+
+This function's anaphoric counterpart is `--every`.
+
+```el
+(-every #'numberp '(1 2 3)) ;; => t
+(--every (string-match-p "x" it) '("axe" "xor")) ;; => 0
+(--every (= it it-index) '(0 1 3)) ;; => nil
 ```
 
 #### -last `(pred list)`

dash.el

@@ -854,6 +854,36 @@ This function's anaphoric counterpart is `--some'."
 (defalias '-any '-some)
 (defalias '--any '--some)
 
+(defmacro --every (form list)
+  "Return non-nil if FORM evals to non-nil for all items in LIST.
+If so, return the last such result of FORM.  Otherwise, once an
+item is reached for which FORM yields nil, return nil without
+evaluating FORM for any further LIST elements.
+Each element of LIST in turn is bound to `it' and its index
+within LIST to `it-index' before evaluating FORM.
+
+This macro is like `--every-p', but on success returns the last
+non-nil result of FORM instead of just t.
+
+This is the anaphoric counterpart to `-every'."
+  (declare (debug (form form)))
+  (let ((a (make-symbol "all")))
+    `(let ((,a t))
+       (--each-while ,list (setq ,a ,form))
+       ,a)))
+
+(defun -every (pred list)
+  "Return non-nil if PRED returns non-nil for all items in LIST.
+If so, return the last such result of PRED.  Otherwise, once an
+item is reached for which PRED returns nil, return nil without
+calling PRED on any further LIST elements.
+
+This function is like `-every-p', but on success returns the last
+non-nil result of PRED instead of just t.
+
+This function's anaphoric counterpart is `--every'."
+  (--every (funcall pred it) list))
+
 (defmacro --last (form list)
   "Anaphoric form of `-last'."
   (declare (debug (form form)))
@@ -949,7 +979,7 @@ See also: `-last-item'."
 (defmacro --any? (form list)
   "Anaphoric form of `-any?'."
   (declare (debug (form form)))
-  `(---truthy? (--some ,form ,list)))
+  `(and (--some ,form ,list) t))
 
 (defun -any? (pred list)
   "Return t if (PRED x) is non-nil for any x in LIST, else nil.
@@ -965,17 +995,34 @@ Alias: `-any-p', `-some?', `-some-p'"
 (defalias '--some-p '--any?)
 
 (defmacro --all? (form list)
-  "Anaphoric form of `-all?'."
+  "Return t if FORM evals to non-nil for all items in LIST.
+Otherwise, once an item is reached for which FORM yields nil,
+return nil without evaluating FORM for any further LIST elements.
+Each element of LIST in turn is bound to `it' and its index
+within LIST to `it-index' before evaluating FORM.
+
+The similar macro `--every' is more widely useful, since it
+returns the last non-nil result of FORM instead of just t on
+success.
+
+Alias: `--all-p', `--every-p', `--every?'.
+
+This is the anaphoric counterpart to `-all?'."
   (declare (debug (form form)))
-  (let ((a (make-symbol "all")))
+  `(and (--every ,form ,list) t))
-    `(let ((,a t))
-       (--each-while ,list ,a (setq ,a ,form))
-       (---truthy? ,a))))
 
 (defun -all? (pred list)
-  "Return t if (PRED x) is non-nil for all x in LIST, else nil.
+  "Return t if (PRED X) is non-nil for all X in LIST, else nil.
+In the latter case, stop after the first X for which (PRED X) is
+nil, without calling PRED on any subsequent elements of LIST.
+
+The similar function `-every' is more widely useful, since it
+returns the last non-nil result of PRED instead of just t on
+success.
+
+Alias: `-all-p', `-every-p', `-every?'.
 
-Alias: `-all-p', `-every?', `-every-p'"
+This function's anaphoric counterpart is `--all?'."
   (--all? (funcall pred it) list))
 
 (defalias '-every? '-all?)

dash.texi

@@ -1722,15 +1722,15 @@ Alias: @code{-any-p}, @code{-some?}, @code{-some-p}
 
 @example
 @group
-(-any? 'even? '(1 2 3))
+(-any? #'numberp '(nil 0 t))
     @result{} t
 @end group
 @group
-(-any? 'even? '(1 3 5))
+(-any? #'numberp '(nil t t))
     @result{} nil
 @end group
 @group
-(-any? 'null '(1 3 5))
+(-any? #'null '(1 3 5))
     @result{} nil
 @end group
 @end example
@@ -1738,18 +1738,26 @@ Alias: @code{-any-p}, @code{-some?}, @code{-some-p}
 
 @anchor{-all?}
 @defun -all? (pred list)
-Return t if (@var{pred} x) is non-nil for all x in @var{list}, else nil.
+Return t if (@var{pred} @var{x}) is non-nil for all @var{x} in @var{list}, else nil.
+In the latter case, stop after the first @var{x} for which (@var{pred} @var{x}) is
+nil, without calling @var{pred} on any subsequent elements of @var{list}.
 
-Alias: @code{-all-p}, @code{-every?}, @code{-every-p}
+The similar function @code{-every} (@pxref{-every}) is more widely useful, since it
+returns the last non-nil result of @var{pred} instead of just t on
+success.
+
+Alias: @code{-all-p}, @code{-every-p}, @code{-every?}.
+
+This function's anaphoric counterpart is @code{--all?}.
 
 @example
 @group
-(-all? 'even? '(1 2 3))
+(-all? #'numberp '(1 2 3))
-    @result{} nil
+    @result{} t
 @end group
 @group
-(-all? 'even? '(2 4 6))
+(-all? #'numberp '(2 t 6))
-    @result{} t
+    @result{} nil
 @end group
 @group
 (--all? (= 0 (% it 2)) '(2 4 6))
@@ -3015,16 +3023,44 @@ This function's anaphoric counterpart is @code{--some}.
 
 @example
 @group
-(-some (lambda (s) (string-match-p "x" s)) '("foo" "axe" "xor"))
+(-some #'stringp '(1 "2" 3))
+    @result{} t
+@end group
+@group
+(--some (string-match-p "x" it) '("foo" "axe" "xor"))
     @result{} 1
 @end group
 @group
-(-some (lambda (s) (string-match-p "x" s)) '("foo" "bar" "baz"))
+(--some (= it-index 3) '(0 1 2))
     @result{} nil
 @end group
+@end example
+@end defun
+
+@anchor{-every}
+@defun -every (pred list)
+Return non-nil if @var{pred} returns non-nil for all items in @var{list}.
+If so, return the last such result of @var{pred}.  Otherwise, once an
+item is reached for which @var{pred} returns nil, return nil without
+calling @var{pred} on any further @var{list} elements.
+
+This function is like @code{-every-p}, but on success returns the last
+non-nil result of @var{pred} instead of just t.
+
+This function's anaphoric counterpart is @code{--every}.
+
+@example
 @group
-(--some (member 'foo it) '((foo bar) (baz)))
+(-every #'numberp '(1 2 3))
-    @result{} (foo bar)
+    @result{} t
+@end group
+@group
+(--every (string-match-p "x" it) '("axe" "xor"))
+    @result{} 0
+@end group
+@group
+(--every (= it it-index) '(0 1 3))
+    @result{} nil
 @end group
 @end example
 @end defun

dev/examples.el

@@ -625,16 +625,33 @@ value rather than consuming a list to produce a single value."
   "Reductions of one or more lists to a boolean value."
 
   (defexamples -any?
-    (-any? 'even? '(1 2 3)) => t
+    (-any? #'numberp '(nil 0 t)) => t
-    (-any? 'even? '(1 3 5)) => nil
+    (-any? #'numberp '(nil t t)) => nil
-    (-any? 'null '(1 3 5)) => nil
+    (-any? #'null '(1 3 5)) => nil
-    (-any? 'null '(1 3 ())) => t
+    (-any? #'null '(1 3 ())) => t
-    (--any? (= 0 (% it 2)) '(1 2 3)) => t)
+    (-any? #'identity '()) => nil
+    (-any? #'identity '(0)) => t
+    (-any? #'identity '(nil)) => nil
+    (--any? (= 0 (% it 2)) '(1 2 3)) => t
+    (--any? (= it it-index) '()) => nil
+    (--any? (= it it-index) '(0)) => t
+    (--any? (= it it-index) '(1)) => nil
+    (--any? (= it it-index) '(1 1)) => t
+    (--any? (= it it-index) '(1 2)) => nil)
 
   (defexamples -all?
-    (-all? 'even? '(1 2 3)) => nil
+    (-all? #'numberp '(1 2 3)) => t
-    (-all? 'even? '(2 4 6)) => t
+    (-all? #'numberp '(2 t 6)) => nil
-    (--all? (= 0 (% it 2)) '(2 4 6)) => t)
+    (--all? (= 0 (% it 2)) '(2 4 6)) => t
+    (-all? #'identity '()) => t
+    (-all? #'identity '(0)) => t
+    (-all? #'identity '(0 1)) => t
+    (-all? #'identity '(nil)) => nil
+    (--all? (= it it-index) '()) => t
+    (--all? (= it it-index) '(0)) => t
+    (--all? (= it it-index) '(1)) => nil
+    (--all? (= it it-index) '(1 1)) => nil
+    (--all? (= it it-index) '(0 1)) => t)
 
   (defexamples -none?
     (-none? 'even? '(1 2 3)) => nil
@@ -1086,7 +1103,9 @@ related predicates."
     (-first #'identity '()) => nil)
 
   (defexamples -some
-    (-some (lambda (s) (string-match-p "x" s)) '("foo" "axe" "xor")) => 1
+    (-some #'stringp '(1 "2" 3)) => t
+    (--some (string-match-p "x" it) '("foo" "axe" "xor")) => 1
+    (--some (= it-index 3) '(0 1 2)) => nil
     (-some (lambda (s) (string-match-p "x" s)) '("foo" "bar" "baz")) => nil
     (--some (member 'foo it) '((foo bar) (baz))) => '(foo bar)
     (--some (plist-get it :bar) '((:foo 1 :bar 2) (:baz 3))) => 2
@@ -1103,6 +1122,32 @@ related predicates."
     (--some it '(1)) => 1
     (--some it '()) => nil)
 
+  (defexamples -every
+    (-every #'numberp '(1 2 3)) => t
+    (--every (string-match-p "x" it) '("axe" "xor")) => 0
+    (--every (= it it-index) '(0 1 3)) => nil
+    (-every #'ignore '()) => t
+    (-every #'ignore '(0)) => nil
+    (-every #'ignore '(0 1)) => nil
+    (--every nil '()) => t
+    (--every nil '(0)) => nil
+    (--every nil '(0 1)) => nil
+    (-every #'identity '()) => t
+    (-every #'identity '(0)) => 0
+    (-every #'identity '(0 1)) => 1
+    (--every it '()) => t
+    (--every it '(1)) => 1
+    (--every it '(1 2)) => 2
+    (--every it-index '()) => t
+    (--every it-index '(1)) => 0
+    (--every it-index '(1 2)) => 1
+    (let ((r 'r)) (-every (lambda (x) (setq r x)) '()) r) => 'r
+    (let ((r 'r)) (-every (lambda (x) (setq r x)) '(nil 1)) r) => nil
+    (let (r) (-every (lambda (x) (setq r x)) '(0 1)) r) => 1
+    (let (i) (--every (ignore (setq i it-index)) '()) i) => nil
+    (let (i) (--every (ignore (setq i it-index)) '(a)) i) => 0
+    (let (i) (--every (ignore (setq i it-index)) '(a b)) i) => 0)
+
   (defexamples -last
     (-last 'even? '(1 2 3 4 5 6 3 3 3)) => 6
     (-last 'even? '(1 3 7 5 9)) => nil