Binary file cws/cw01.pdf has changed
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/graphics.sty Thu Nov 10 04:02:45 2016 +0000
@@ -0,0 +1,21 @@
+\usepackage{tikz}
+\usepackage{pgf}
+\usetikzlibrary{positioning}
+\usetikzlibrary{calc}
+\usetikzlibrary{automata}
+\usetikzlibrary{arrows}
+\usetikzlibrary{backgrounds}
+\usetikzlibrary{fit}
+\usepackage{tikz-qtree}
+\usepackage{graphicx}
+\usepackage{pgfplots}
+
+\pgfplotsset{compat=1.11}
+
+\newenvironment{bubble}[1][]{%
+\addtolength{\leftmargini}{4mm}%
+\begin{tikzpicture}[baseline=(current bounding box.north)]%
+\draw (0,0) node[inner sep=2mm,fill=cream,ultra thick,draw=red,rounded corners=2mm]%
+\bgroup\begin{minipage}{#1}\raggedright{}}
+{\end{minipage}\egroup;%
+\end{tikzpicture}\bigskip}
Binary file pics/laptop.png has changed
Binary file pics/servers.png has changed
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/hello-world.scala Thu Nov 10 04:02:45 2016 +0000
@@ -0,0 +1,3 @@
+object Hello extends App {
+ println("hello world")
+}
--- a/progs/lecture1.scala Thu Nov 10 01:31:12 2016 +0000
+++ b/progs/lecture1.scala Thu Nov 10 04:02:45 2016 +0000
@@ -43,6 +43,7 @@
// some methods take more than one argument
println(lst.mkString("[", ",", "]"))
+
// Conversion methods
//====================
@@ -52,7 +53,19 @@
1.toDouble
+// useful list methods
+
+List(1,2,3,4).length
List(1,2,3,4).reverse
+List(1,2,3,4).max
+List(1,2,3,4).min
+List(1,2,3,4).sum
+List(1,2,3,4).take(2).sum
+List(1,2,3,4).drop(2).sum
+List(1,2,3,4,3).indexOf(3)
+
+"1,2,3,4,5".split(",").toList
+
// Types
//=======
@@ -107,10 +120,20 @@
// Hello World
//=============
-// show an example of a stand-alone scala file
-// remind that in the course work you are asked a
-// plain scala "work-sheet"
+// an example of a stand-alone scala file;
+// in the coursework students must submit
+// plain scala "work-sheets"
+object Hello extends App {
+ println("hello world")
+}
+
+// can be called with
+//
+// $> scalac hello-world.scala
+// $> scala Hello
+//
+// $> java -cp /usr/local/src/scala/lib/scala-library.jar:. Hello
// Function Definitions
@@ -175,6 +198,11 @@
// Assert/Testing
//================
+assert(gcd(48, 18) == 6)
+
+assert(gcd(48, 18) == 5, "The gcd test failed")
+
+
// For-Comprehensions (not For-Loops)
//====================================
@@ -191,6 +219,14 @@
mult_table.sliding(10,10).mkString("\n")
+// with if-predicates
+
+for (n <- (1 to 3).toList;
+ m <- (1 to 3).toList;
+ if (n + m) % 2 == 0) yield (n, m)
+
+
+
// with patterns
for ((m, n) <- List((1, 4), (2, 3), (3, 2), (4, 1))) yield m + n
@@ -199,5 +235,133 @@
+// with only a side-effect (no list is produced)
+// has no "yield"
+
+for (n <- (1 to 10)) println(n)
+
+
+// concurrency (ONLY WORKS IN 2.11.8)
+for (n <- (1 to 10)) println(n)
+for (n <- (1 to 10).par) println(n)
+
+
+
+// for testing time
+def time_needed[T](i: Int, code: => T) = {
+ val start = System.nanoTime()
+ for (j <- 1 to i) code
+ val end = System.nanoTime()
+ ((end - start) / i / 1.0e9) + " secs"
+}
+
+val list = (1 to 1000000).toList
+time_needed(10, for (n <- list) yield n + 42)
+time_needed(10, for (n <- list.par) yield n + 42)
+
+
+
// Webpages
//==========
+
+import io.Source
+
+val url = """http://www.inf.kcl.ac.uk/staff/urbanc/"""
+Source.fromURL(url)("ISO-8859-1").mkString
+
+
+
+def price_lookup(symbol: String): String = {
+ val url = "http://finance.yahoo.com/d/quotes.csv?s=" + symbol + "&f=snl1"
+ Source.fromURL(url).mkString.drop(1).dropRight(2)
+}
+
+price_lookup("GOOG")
+price_lookup("AAPL")
+
+
+val companies =
+ List("GOOG", "AAPL", "MSFT", "IBM", "FB", "YHOO", "AMZN", "BIDU")
+
+for (s <- companies.par) println(price_lookup(s))
+
+
+// A Web Crawler
+//===============
+
+import io.Source
+import scala.util.matching.Regex
+import scala.util._
+
+// gets the first 10K of a web-page
+def get_page(url: String) : String = {
+ Try(Source.fromURL(url)("ISO-8859-1").take(10000).mkString).
+ getOrElse { println(s" Problem with: $url"); ""}
+}
+
+// regex for URLs
+val http_pattern = """"https?://[^"]*"""".r
+
+// drops the first and last character from a string
+def unquote(s: String) = s.drop(1).dropRight(1)
+
+def get_all_URLs(page: String): Set[String] =
+ http_pattern.findAllIn(page).map(unquote).toSet
+
+// naive version of crawl - searches until a given depth,
+// visits pages potentially more than once
+def crawl(url: String, n: Int): Unit = {
+ if (n == 0) ()
+ else {
+ println(s"Visiting: $n $url")
+ for (u <- get_all_URLs(get_page(url))) crawl(u, n - 1)
+ }
+}
+
+// some starting URLs for the crawler
+val startURL = """http://www.inf.kcl.ac.uk/staff/urbanc"""
+//val startURL = """http://www.inf.kcl.ac.uk/staff/mcburney"""
+
+crawl(startURL, 2)
+
+
+
+
+// Adding your own methods to Strings
+//====================================
+
+// imagine you want to implement an additional
+// method to strings, like
+//
+// "HAL".increment
+//
+// you can avoid ugly fudges, like a MyString
+// class by using implicit conversions
+
+
+implicit class MyString(s: String) {
+ def increment = for (c <- s) yield (c + 1).toChar
+}
+
+"HAL".increment
+
+
+// Further Information
+//=====================
+
+// Scala download
+//
+// http://www.scala-lang.org
+
+// Eclipse for Scala
+//
+// http://scala-ide.org/download/sdk.html
+
+
+// library docs
+//
+// http://www.scala-lang.org/api/current/
+
+// tutorials
+//
+// http://docs.scala-lang.org/tutorials/
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/slides/Point.java Thu Nov 10 04:02:45 2016 +0000
@@ -0,0 +1,12 @@
+public class Point {
+ private final int x, y;
+
+ public Point(int x, int y) {
+ this.x = x;
+ this.y = y;
+ }
+
+ public int x() { return x; }
+
+ public int y() { return y; }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/slides/Point.scala Thu Nov 10 04:02:45 2016 +0000
@@ -0,0 +1,1 @@
+class Point(val x: Int, val y: Int)
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/slides/URLReader.java Thu Nov 10 04:02:45 2016 +0000
@@ -0,0 +1,32 @@
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.Scanner;
+
+public class URLReader {
+
+ public static String readURL(String sUrl) {
+ StringBuilder buf = new StringBuilder();
+ Scanner in = null;
+
+ try {
+ URL url = new URL(sUrl);
+ in = new Scanner(url.openStream());
+
+ while (in.hasNextLine()) {
+ buf.append(in.nextLine() + "\n");
+ }
+ return buf.toString();
+
+ } catch (MalformedURLException e) {
+ System.err.println(e);
+ } catch (IOException e) {
+ System.err.println(e);
+ } finally {
+ if (in != null) {
+ in.close();
+ }
+ }
+ return null;
+ }
+}
\ No newline at end of file
Binary file slides/slides01.pdf has changed
--- a/slides/slides01.tex Thu Nov 10 01:31:12 2016 +0000
+++ b/slides/slides01.tex Thu Nov 10 04:02:45 2016 +0000
@@ -1,6 +1,6 @@
\documentclass[dvipsnames,14pt,t,xelatex]{beamer}
\usepackage{../slides}
-%\usepackage{../graphics}
+\usepackage{../graphics}
\usepackage{../langs}
%\usepackage{../data}
@@ -79,7 +79,10 @@
\frametitle{Why Scala?}
\begin{itemize}
-\item bla
+\item compiles to the JVM (also JavaScript, X86)\medskip
+\item integrates seamlessly with Java\medskip
+\item combines {\bf functional} and {\bf object-oriented} programming\medskip
+\item allows often to write more elegant code
\end{itemize}
\end{frame}
@@ -87,6 +90,29 @@
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}[c]
+\frametitle{Java vs Scala}
+
+{\lstset{language=java}\fontsize{12}{12}\selectfont
+\texttt{\lstinputlisting{Point.java}}}
+
+{\lstset{language=scala}\fontsize{12}{12}\selectfont
+\texttt{\lstinputlisting{Point.scala}}}
+
+\begin{textblock}{6}(13,3)
+\textbf{\large Java}
+\end{textblock}
+
+\begin{textblock}{6}(13,13.2)
+\textbf{\large Scala}
+\end{textblock}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
\frametitle{Types}
\begin{itemize}
@@ -124,6 +150,62 @@
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
+\frametitle{An Http Request}
+
+\begin{textblock}{1}(2,5)
+\begin{tabular}{c}
+\includegraphics[scale=0.15]{../pics/servers.png}\\[-2mm]
+\small Server
+\end{tabular}
+\end{textblock}
+
+\begin{textblock}{1}(5.6,4)
+ \begin{tikzpicture}[scale=1.1]
+ \draw[white] (0,1) node (X) {};
+ \draw[white] (2,1) node (Y) {};
+ \draw[white] (0,0) node (X1) {};
+ \draw[white] (2,0) node (Y1) {};
+ \draw[white] (0,-1) node (X2) {};
+ \draw[white] (2,-1) node (Y2) {};
+ \draw[red, <-, line width = 2mm] (X) -- (Y);
+ \node [inner sep=5pt,label=above:\textcolor{black}{GET request}] at ($ (X)!.5!(Y) $) {};
+ \draw[red, ->, line width = 2mm] (X1) -- (Y1);
+ \node [inner sep=5pt,label=above:\textcolor{black}{webpage}] at ($ (X1)!.5!(Y1) $) {};
+ \draw[red, <-, line width = 2mm] (X2) -- (Y2);
+ \node [inner sep=7pt,label=above:\textcolor{black}{POST data}] at ($ (X2)!.5!(Y2) $) {};
+ \end{tikzpicture}
+\end{textblock}
+
+
+\begin{textblock}{1}(9,5.5)
+\begin{tabular}{c}
+\includegraphics[scale=0.15]{../pics/laptop.png}\\[-2mm]
+\small Browser
+\end{tabular}
+\end{textblock}
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
+
+{\lstset{language=Java}\fontsize{7}{8}\selectfont
+\texttt{\lstinputlisting{URLReader.java}}}
+
+\only<2>{
+\begin{textblock}{5}(12,2)
+\includegraphics[scale=0.50]{../pics/skeleton.jpg}\\
+\end{textblock}}
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+
\end{document}
%%% Local Variables: 
