# HG changeset patch
# User IBBoard <dev@ibboard.co.uk>
# Date 1559849202 -3600
# Node ID a83309cdf5d35e4d5c06d11a150cd1f9727a61e5
# Parent  29025305bbb7441f78412af107f2811e046020eb
Add details of Clojure's loop recursion approach

diff -r 29025305bbb7 -r a83309cdf5d3 6-Clojure/README.txt
--- a/6-Clojure/README.txt	Sat Jun 01 20:10:59 2019 +0100
+++ b/6-Clojure/README.txt	Thu Jun 06 20:26:42 2019 +0100
@@ -79,4 +79,7 @@
 
 As well as the map function, there's "apply" and "filter".
 
-Also, some helper functions exist, like "odd?".
\ No newline at end of file
+Also, some helper functions exist, like "odd?".
+
+Functional languages do lazy tail recursion. Unless they're Clojure, because the JVM doesn't support it. Clojure does it with a  "loop" and a "recur" function. "loop" takes x and y with initial values and a function to call. See loop_recur.clj.
+
diff -r 29025305bbb7 -r a83309cdf5d3 6-Clojure/loop_recur.clj
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/6-Clojure/loop_recur.clj	Thu Jun 06 20:26:42 2019 +0100
@@ -0,0 +1,16 @@
+; Define a function that takes a single parameter (which needs to be a list-like thing)
+(defn size [_vec]
+    ; Loop over _list with starting value of our parameter and _size with starting value of 0
+    (loop [_list _vec, _size 0]
+        ; Code to execute is just an "if" block
+        (if (empty? _list)
+            ; if our list is empty, return the size
+            _size
+            ; else call loop's body again (the "if" block) but this time pass in
+            ; the tail of the list and the incremented size counter 
+            (recur (rest _list) (inc _size)))))
+
+(println (size [1 2 3 5 7 9]))
+(println (size (list 1 2 3)))
+(println (size #{}))
+(println (size #{1}))
\ No newline at end of file