From 41649089e35cfb5a9c4d3b518e92c7eaaa9d424d Mon Sep 17 00:00:00 2001
From: Johan Andersson <johan.rejeep@gmail.com>
Date: Mon, 12 Aug 2013 21:33:46 +0200
Subject: [PATCH] Add -min, -max, -min-by and -max-by.

---
 README.md       | 44 ++++++++++++++++++++++++++++++++++++++++++++
 dash.el         | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 dev/examples.el | 22 ++++++++++++++++++++++
 3 files changed, 114 insertions(+)

diff --git a/README.md b/README.md
index 51209ae..98354b8 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,10 @@ Or you can just dump `dash.el` in your load path somewhere.
 * [-count](#-count-pred-list) `(pred list)`
 * [-sum](#-sum-list) `(list)`
 * [-product](#-product-list) `(list)`
+* [-min](#-min-x-rest-xs) `(x &rest xs)`
+* [-min-by](#-min-by-pred-list) `(pred list)`
+* [-max](#-max-x-rest-xs) `(x &rest xs)`
+* [-max-by](#-max-by-pred-list) `(pred list)`
 * [-any?](#-any-pred-list) `(pred list)`
 * [-all?](#-all-pred-list) `(pred list)`
 * [-none?](#-none-pred-list) `(pred list)`
@@ -315,6 +319,46 @@ Return the product of `list`.
 (-product '(1 2 3)) ;; => 6
 ```
 
+### -min `(x &rest xs)`
+
+Return the smallest value of all arguments.
+
+```cl
+(-min 0) ;; => 0
+(-min 1) ;; => 1
+(-min 1 2 3) ;; => 1
+```
+
+### -min-by `(pred list)`
+
+Call `pred` for each item in `list` and return item with smallest value.
+
+```cl
+(-min-by 'identity '()) ;; => nil
+(-min-by 'identity '(1)) ;; => 1
+(--min-by (cdr it) '((a . 1) (b . 2) (c . 3))) ;; => '(a . 1)
+```
+
+### -max `(x &rest xs)`
+
+Return the largest value of all arguments.
+
+```cl
+(-max 0) ;; => 0
+(-max 1) ;; => 1
+(-max 1 2 3) ;; => 3
+```
+
+### -max-by `(pred list)`
+
+Call `pred` for each item in `list` and return item with largest value.
+
+```cl
+(-max-by 'identity '()) ;; => nil
+(-max-by 'identity '(1)) ;; => 1
+(--max-by (cdr it) '((a . 1) (b . 2) (c . 3))) ;; => '(c . 3)
+```
+
 ### -any? `(pred list)`
 
 Returns t if (`pred` x) is non-nil for any x in `list`, else nil.
diff --git a/dash.el b/dash.el
index 31e9a83..ba5ec25 100644
--- a/dash.el
+++ b/dash.el
@@ -893,6 +893,48 @@ Returns nil if N is less than 1."
   "Return the product of LIST."
   (apply '* list))
 
+(defun -min (x &rest xs)
+  "Return the smallest value of all arguments."
+  (apply 'min (cons x xs)))
+
+(defun -min-by (pred list)
+  "Call PRED for each item in LIST and return item with smallest value."
+  (let (min-item (min-value most-positive-fixnum))
+    (-each
+     list
+     (lambda (item)
+       (let ((item-value (funcall pred item)))
+         (when (< item-value min-value)
+           (setq min-value item-value)
+           (setq min-item item)))))
+    min-item))
+
+(defmacro --min-by (form list)
+  "Anaphoric form of `-min-by'."
+  (declare (debug t))
+  `(-min-by (lambda (it) ,form) ,list))
+
+(defun -max (x &rest xs)
+  "Return the largest value of all arguments."
+  (apply 'max (cons x xs)))
+
+(defun -max-by (pred list)
+  "Call PRED for each item in LIST and return item with largest value."
+  (let (max-item (max-value most-negative-fixnum))
+    (-each
+     list
+     (lambda (item)
+       (let ((item-value (funcall pred item)))
+         (when (> item-value max-value)
+           (setq max-value item-value)
+           (setq max-item item)))))
+    max-item))
+
+(defmacro --max-by (form list)
+  "Anaphoric form of `-max-by'."
+  (declare (debug t))
+  `(-max-by (lambda (it) ,form) ,list))
+
 (eval-after-load "lisp-mode"
   '(progn
      (let ((new-keywords '(
@@ -998,6 +1040,12 @@ Returns nil if N is less than 1."
                            "-cons*"
                            "-sum"
                            "-product"
+                           "-min"
+                           "-min-by"
+                           "--min-by"
+                           "-max"
+                           "-max-by"
+                           "--max-by"
                            ))
            (special-variables '(
                                 "it"
diff --git a/dev/examples.el b/dev/examples.el
index e035320..06105bd 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -109,6 +109,28 @@
   (-product '(1)) => 1
   (-product '(1 2 3)) => 6)
 
+(defexamples -min
+  (-min 0) => 0
+  (-min 1) => 1
+  (-min 1 2 3) => 1)
+
+(defexamples -min-by
+  (-min-by 'identity '()) => nil
+  (-min-by 'identity '(1)) => 1
+  (--min-by (cdr it) '((a . 1) (b . 2) (c . 3))) => '(a . 1)
+  (-min-by (lambda (x) (string-to-int x)) '("1" "2" "3")) => "1")
+
+(defexamples -max
+  (-max 0) => 0
+  (-max 1) => 1
+  (-max 1 2 3) => 3)
+
+(defexamples -max-by
+  (-max-by 'identity '()) => nil
+  (-max-by 'identity '(1)) => 1
+  (--max-by (cdr it) '((a . 1) (b . 2) (c . 3))) => '(c . 3)
+  (-max-by (lambda (x) (string-to-int x)) '("1" "2" "3")) => "3")
+
 (defexamples -any?
   (-any? 'even? '(1 2 3)) => t
   (-any? 'even? '(1 3 5)) => nil