From f58864deda9e5bdceea530b8dfb3654a7a1fbd24 Mon Sep 17 00:00:00 2001 From: Colin Jones Date: Thu, 11 Feb 2010 12:13:55 +0800 Subject: [PATCH] adding about map/filter/reduce --- koans/about_higher_order_functions.clj | 32 ++++++++++++++++++++++++++ koans/path_to_enlightenment.clj | 1 + 2 files changed, 33 insertions(+) create mode 100644 koans/about_higher_order_functions.clj diff --git a/koans/about_higher_order_functions.clj b/koans/about_higher_order_functions.clj new file mode 100644 index 0000000..fc9ea67 --- /dev/null +++ b/koans/about_higher_order_functions.clj @@ -0,0 +1,32 @@ +(meditations + "The map function relates a sequence to another" + (= [__ __ __] (map (fn [x] (* 4 x)) [1 2 3])) + + "You may create that mapping" + (= [1 4 9 16 25] (map (fn [x] __) [1 2 3 4 5])) + + "Or use the names of existing functions" + (= __ (map nil? [:a :b nil :c :d])) + + "A filter can be strong" + (= __ (filter (fn [x] false) '(:anything :goes :here))) + + "Or very weak" + (= '(:anything :goes :here) (filter (fn [x] __) '(:anything :goes :here))) + + "Or somewhere in between" + (= [10 20 30] (filter (fn [x] __) [10 20 30 40 50 60 70 80])) + + "Maps and filters may be combined" + (= [10 20 30] (map (fn [x] __) (filter (fn [x] __) [1 2 3 4 5 6 7 8]))) + + "Reducing can increase the result" + (= __ (reduce (fn [a b] (* a b)) [1 2 3 4])) + + "You can start somewhere else" + (= 2400 (reduce (fn [a b] (* a b)) __ [1 2 3 4])) + + "Numbers are not the only things one can reduce" + (= "longest" (reduce (fn [a b] + (if (< __ __) b a)) + ["which" "word" "is" "longest"]))) diff --git a/koans/path_to_enlightenment.clj b/koans/path_to_enlightenment.clj index 67dfb52..ee2d974 100644 --- a/koans/path_to_enlightenment.clj +++ b/koans/path_to_enlightenment.clj @@ -18,4 +18,5 @@ (load "about_maps") (load "about_functions") (load "about_conditionals") +(load "about_higher_order_functions") (println "You have acheived clojure enlightenment. Namaste.")