Changes between Version 70 and Version 71 of Clojure Client Tutorial

Timestamp:

Aug 23, 2011 2:10:57 PM (13 years ago)

Author:

kedwar10

Comment:

--

Clojure Client Tutorial

@@ -25 +25 @@
 * Clojure Docs [http://clojuredocs.org/].
 * Statistical Computing [http://incanter.org/]
-* Marginalia (literate computing) [http://fogus.me/fun/marginalia/]
+* Literate Programming [http://fogus.me/fun/marginalia/]
 * Pattern Matching and Predicate Dispatch [https://github.com/swannodette/match]
 * Logic Programming [https://github.com/clojure/core.logic]
@@ -93 +93 @@
 user=> (map inc [1 2 3 4 5])
 (2 3 4 5 6)
-user=> (map (fn [e] (* e 2)) [1 2 3 4 5]) ; an anonymous function
+user=> (map (fn [e] (* e 2)) [1 2 3 4 5]) ; an anonymous function that doubles its argument
 (2 4 6 8 10)
 user=> (map #(* % 2) [1 2 3 4 5]) ; same, but with alternative syntax        
 (2 4 6 8 10)
-user=> ((juxt inc dec) 1)          
-[2 0]
-}}}
-
-The client behaviour more closely corresponds to the "reduce" function.
-
-{{{
 user=> (reduce + [1 2 3 4 5])
 15
-}}} 
+user=> (reduce #(cons %2 %1) (list) [1 2 3 4 5]) ; reverse a list
+(5 4 3 2 1)
+}}}
+
+Another useful concept is that of "closures".  Generally these appear in the context of a "let over lambda".  For example,
+
+{{{
+user=> (let [a (atom 0)]
+         (defn counter [] 
+           (swap! a inc)))
+#'user/counter
+user=> (counter)
+1
+user=> (counter)
+2
+user=> (counter)
+3
+}}}
+
+In this case, counter "closes" over the a lexical variable "a" and prevents it from going out of scope. 
 
 === Basic Functionality ===