File 0061-Retire-two-myths.patch of Package erlang
From 1cc8044ffc6073749e34dcf1434f02272fe4b457 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 7 Jun 2016 15:14:16 +0200
Subject: [PATCH 1/4] Retire two myths
---
system/doc/efficiency_guide/myths.xml | 31 ++-----------
system/doc/efficiency_guide/part.xml | 1 +
system/doc/efficiency_guide/retired_myths.xml | 63 +++++++++++++++++++++++++++
3 files changed, 67 insertions(+), 28 deletions(-)
create mode 100644 system/doc/efficiency_guide/retired_myths.xml
diff --git a/system/doc/efficiency_guide/myths.xml b/system/doc/efficiency_guide/myths.xml
index 5d3ad78b2..7e2f3c846 100644
--- a/system/doc/efficiency_guide/myths.xml
+++ b/system/doc/efficiency_guide/myths.xml
@@ -24,7 +24,7 @@
The Initial Developer of the Original Code is Ericsson AB.
</legalnotice>
- <title>The Eight Myths of Erlang Performance</title>
+ <title>The Six Myths of Erlang Performance</title>
<prepared>Bjorn Gustavsson</prepared>
<docno></docno>
<date>2007-11-10</date>
@@ -35,38 +35,13 @@
<marker id="myths"></marker>
<p>Some truths seem to live on well beyond their best-before date,
perhaps because "information" spreads faster from person-to-person
- than a single release note that says, for example, that funs
- have become faster.</p>
+ than a single release note that says, for example, that body-recursive
+ calls have become faster.</p>
<p>This section tries to kill the old truths (or semi-truths) that have
become myths.</p>
<section>
- <title>Myth: Funs are Slow</title>
- <p>Funs used to be very slow, slower than <c>apply/3</c>.
- Originally, funs were implemented using nothing more than
- compiler trickery, ordinary tuples, <c>apply/3</c>, and a great
- deal of ingenuity.</p>
-
- <p>But that is history. Funs was given its own data type
- in R6B and was further optimized in R7B.
- Now the cost for a fun call falls roughly between the cost for a call
- to a local function and <c>apply/3</c>.</p>
- </section>
-
- <section>
- <title>Myth: List Comprehensions are Slow</title>
-
- <p>List comprehensions used to be implemented using funs, and in the
- old days funs were indeed slow.</p>
-
- <p>Nowadays, the compiler rewrites list comprehensions into an ordinary
- recursive function. Using a tail-recursive function with
- a reverse at the end would be still faster. Or would it?
- That leads us to the next myth.</p>
- </section>
-
- <section>
<title>Myth: Tail-Recursive Functions are Much Faster
Than Recursive Functions</title>
diff --git a/system/doc/efficiency_guide/part.xml b/system/doc/efficiency_guide/part.xml
index 6e10a0c03..5673ddd32 100644
--- a/system/doc/efficiency_guide/part.xml
+++ b/system/doc/efficiency_guide/part.xml
@@ -39,5 +39,6 @@
<xi:include href="drivers.xml"/>
<xi:include href="advanced.xml"/>
<xi:include href="profiling.xml"/>
+ <xi:include href="retired_myths.xml"/>
</part>
diff --git a/system/doc/efficiency_guide/retired_myths.xml b/system/doc/efficiency_guide/retired_myths.xml
new file mode 100644
index 000000000..37f46566c
--- /dev/null
+++ b/system/doc/efficiency_guide/retired_myths.xml
@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+ <header>
+ <copyright>
+ <year>2016</year>
+ <year>2016</year>
+ <holder>Ericsson AB, All Rights Reserved</holder>
+ </copyright>
+ <legalnotice>
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+ The Initial Developer of the Original Code is Ericsson AB.
+ </legalnotice>
+ <marker id="retired_myths"/>
+ <title>Retired Myths</title>
+ <prepared>Bjorn Gustavsson</prepared>
+ <docno></docno>
+ <date>2016-06-07</date>
+ <rev></rev>
+ <file>retired_myths.xml</file>
+ </header>
+
+ <p>We belive that the truth finally has caught with the following,
+ retired myths.</p>
+
+ <section>
+ <title>Myth: Funs are Slow</title>
+ <p>Funs used to be very slow, slower than <c>apply/3</c>.
+ Originally, funs were implemented using nothing more than
+ compiler trickery, ordinary tuples, <c>apply/3</c>, and a great
+ deal of ingenuity.</p>
+
+ <p>But that is history. Funs was given its own data type
+ in R6B and was further optimized in R7B.
+ Now the cost for a fun call falls roughly between the cost for a call
+ to a local function and <c>apply/3</c>.</p>
+ </section>
+
+ <section>
+ <title>Myth: List Comprehensions are Slow</title>
+
+ <p>List comprehensions used to be implemented using funs, and in the
+ old days funs were indeed slow.</p>
+
+ <p>Nowadays, the compiler rewrites list comprehensions into an ordinary
+ recursive function. Using a tail-recursive function with
+ a reverse at the end would be still faster. Or would it?
+ That leads us to the myth that tail-recursive functions are faster
+ than body-recursive functions.</p>
+ </section>
+</chapter>
--
2.11.0
