[elpa] externals/dash ab99be6 335/426: Add -fix

[Phillip Lord]

branch: externals/dash
commit ab99be66369d4c9a0138f3226fc13f580dd6ff0c
Author: Matus Goljer <address@hidden>
Commit: Matus Goljer <address@hidden>

    Add -fix
---
 README.md       |   12 ++++++++++++
 dash.el         |   16 ++++++++++++++++
 dev/examples.el |    8 +++++++-
 3 files changed, 35 insertions(+), 1 deletions(-)

diff --git a/README.md b/README.md
index d30cd76..2b44acf 100644
--- a/README.md
+++ b/README.md
@@ -186,6 +186,7 @@ Other list functions not fit to be classified elsewhere.
 * [-butlast](#-butlast-list) `(list)`
 * [-sort](#-sort-comparator-list) `(comparator list)`
 * [-list](#-list-rest-args) `(&rest args)`
+* [-fix](#-fix-fn-list) `(fn list)`
 
 ### Tree operations
 
@@ -1467,6 +1468,17 @@ not, return a list with `args` as elements.
 (-list 1 2 3) ;; => '(1 2 3)
 ```
 
+#### -fix `(fn list)`
+
+Compute the (least) fixpoint of `fn` with initial input `list`.
+
+`fn` is called at least once, results are compared with `equal`.
+
+```cl
+(-fix (lambda (l) (-non-nil (--mapcat (-split-at (/ (length it) 2) it) l))) 
'((1 2 3 4 5 6))) ;; => '((1) (2) (3) (4) (5) (6))
+(let ((data '(("starwars" "scifi") ("jedi" "starwars" "warrior")))) (--fix 
(-uniq (--mapcat (cons it (cdr (assoc it data))) it)) '("jedi" "book"))) ;; => 
'("jedi" "starwars" "warrior" "scifi" "book")
+```
+
 
 ## Tree operations
 
diff --git a/dash.el b/dash.el
index 76a8e75..c90d3bf 100644
--- a/dash.el
+++ b/dash.el
@@ -1371,6 +1371,20 @@ N is the length of the returned list."
   (declare (debug (form form form)))
   `(-iterate (lambda (it) ,form) ,init ,n))
 
+(defun -fix (fn list)
+  "Compute the (least) fixpoint of FN with initial input LIST.
+
+FN is called at least once, results are compared with `equal'."
+  (let ((re (funcall fn list)))
+    (while (not (equal list re))
+      (setq list re)
+      (setq re (funcall fn re)))
+    re))
+
+(defmacro --fix (form list)
+  "Anaphoric form of `-fix'."
+  `(-fix (lambda (it) ,form) ,list))
+
 (defun -unfold (fun seed)
   "Build a list from SEED using FUN.
 
@@ -1734,6 +1748,8 @@ structure such as plist or alist."
                              "--min-by"
                              "-iterate"
                              "--iterate"
+                             "-fix"
+                             "--fix"
                              "-unfold"
                              "--unfold"
                              "-cons-pair?"
diff --git a/dev/examples.el b/dev/examples.el
index 5e1197d..04fb8c3 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -572,7 +572,13 @@ new list."
     (-list 1) => '(1)
     (-list 1 2 3) => '(1 2 3)
     (-list '(1 2 3) => '(1 2 3))
-    (-list '((1) (2)) => '((1) (2)))))
+    (-list '((1) (2)) => '((1) (2))))
+
+  (defexamples -fix
+    (-fix (lambda (l) (-non-nil (--mapcat (-split-at (/ (length it) 2) it) 
l))) '((1 2 3 4 5 6))) => '((1) (2) (3) (4) (5) (6))
+    (let ((data '(("starwars" "scifi")
+                  ("jedi" "starwars" "warrior"))))
+      (--fix (-uniq (--mapcat (cons it (cdr (assoc it data))) it)) '("jedi" 
"book"))) => '("jedi" "starwars" "warrior" "scifi" "book")))
 
 (def-example-group "Tree operations"
   "Functions pretending lists are trees."