Modernize section about list handling and list comprehensions

1 files changed, 12 insertions, 4 deletions

diff --git a/system/doc/efficiency_guide/listhandling.xml b/system/doc/efficiency_guide/listhandling.xml
index 2ebc877820..ec258d7c2a 100644
--- a/system/doc/efficiency_guide/listhandling.xml
+++ b/system/doc/efficiency_guide/listhandling.xml
@@ -90,7 +90,7 @@ tail_recursive_fib(N, Current, Next, Fibs) ->
     <p>Lists comprehensions still have a reputation for being slow.
     They used to be implemented using funs, which used to be slow.</p>
 
-    <p>In recent Erlang/OTP releases (including R12B), a list comprehension:</p>
+    <p>A list comprehension:</p>
 
     <code type="erl"><![CDATA[
 [Expr(E) || E <- List]]]></code>
@@ -102,7 +102,7 @@ tail_recursive_fib(N, Current, Next, Fibs) ->
     [Expr(E)|'lc^0'(Tail, Expr)];
 'lc^0'([], _Expr) -> [].</code>
 
-    <p>In R12B, if the result of the list comprehension will <em>obviously</em>
+    <p>If the result of the list comprehension will <em>obviously</em>
     not be used, a list will not be constructed. For example, in this code:</p>
     
     <code type="erl"><![CDATA[
@@ -131,6 +131,14 @@ some_function(...),
     'lc^0'(Tail, Expr);
 'lc^0'([], _Expr) -> [].</code>
 
+    <p>The compiler also understands that assigning to '_' means that
+    the value will not used. Therefore, the code in the following example
+    will also be optimized:</p>
+
+    <code type="erl"><![CDATA[
+_ = [io:put_chars(E) || E <- List],
+ok.]]></code>
+
   </section>
 
   <section>
@@ -209,11 +217,11 @@ some_function(...),
   <section>
     <title>Recursive List Functions</title>
 
-    <p>In Section 7.2, the following myth was exposed:
+    <p>In section about myths, the following myth was exposed:
     <seealso marker="myths#tail_recursive">Tail-Recursive Functions
     are Much Faster Than Recursive Functions</seealso>.</p>
 
-    <p>To summarize, in R12B there is usually not much difference between
+    <p>There is usually not much difference between
     a body-recursive list function and tail-recursive function that reverses
     the list at the end. Therefore, concentrate on writing beautiful code
     and forget about the performance of your list functions. In the