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\renewcommand{\slidecaption}{PEP (Scala) 02, King's College London}

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\begin{frame}[t]

\frametitle{%

  \begin{tabular}{@ {}c@ {}}

  \\[5mm]

  \huge PEP Scala (2) 

  \end{tabular}}

  \normalsize

  \begin{center}

  \begin{tabular}{ll}

    Email:  & christian.urban at kcl.ac.uk\\

    Office: & N\liningnums{7.07} (North Wing, Bush House)\\

    Slides \& Code: & KEATS\medskip\\

    Office Hours: &  Mondays 12:00 -- 14:00\\

  \end{tabular}

  \end{center}

\end{frame}

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\begin{frame}[c,fragile]

\frametitle{Scala on Lab Computers}

\begin{lstlisting}[language={},numbers=none,

  basicstyle=\ttfamily\small,xleftmargin=-2mm]

$ /usr/share/scala/bin/scala

Welcome to Scala 2.12.6 (Java HotSpot(TM) 64-Bit

Server VM, Java 10.0.1). Type in expressions for

evaluation. Or try :help.

scala>

\end{lstlisting}%$

\end{frame}

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\begin{frame}[c]

\frametitle{Scala on Lab Computers}

Avoid at all costs, even in comments

\begin{itemize}

\item \texttt{var} \only<2>{$\quad\Rightarrow\;$\texttt{Var}}

\item \texttt{return} \only<2>{$\quad\Rightarrow\;$\texttt{Return}}

\item \texttt{.par}

\item \texttt{ListBuffer}

\item \texttt{mutable}  

\end{itemize}

\end{frame}

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\begin{frame}[t]

\frametitle{For-Comprehensions Again}

\begin{center}

  \begin{tikzpicture}[scale=1,

                      node/.style={

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                      very thick,draw=black!50,

                      minimum height=18mm, minimum width=20mm,

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  \node (A0) at (0.1,0) {\texttt{\textcolor{purple}{\textbf{for}} (\alert<2->{n} <- List(}};

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  \node (A4) at (5.0,0) {\texttt{\phantom{,}4,}};

  \node (A5) at (5.9,0) {\texttt{\phantom{))}5))}};

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  \node (B3) at (4.9,-3) {\texttt{\phantom{,}9,}};

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\end{center}

\onslide<3>{This is for when the for-comprehension\\ \textbf{yields / produces} a result.}

\end{frame}

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\begin{frame}[t]

\frametitle{For-Comprehensions Again}

\begin{center}

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 \end{tikzpicture}

\end{center}\bigskip

The second version is in case the for \textbf{does not}

produce any result.

\end{frame}

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\begin{frame}[t]

\frametitle{Why Scala? No null!}

\begin{itemize}

\item \large {\bf You can avoid \textcolor{blue}{\texttt{null}}}:

\end{itemize}

\begin{textblock}{6}(1,5)

  \begin{bubble}[10.5cm]\small

      ``I call it my billion-dollar mistake. It was the invention of

      the null reference in 1965. At that time, I was designing the

      first comprehensive type system for references in an object

      oriented language (ALGOL W). My goal was to ensure that all use

      of references should be absolutely safe, with checking performed

      automatically by the compiler. But I couldn't resist the

      temptation to put in a null reference, simply because it was so

      easy to implement. This has led to innumerable errors,

      vulnerabilities, and system crashes, which have probably caused

      a billion dollars of pain and damage in the last forty years.''

      \hfill Sir Tony (Hoare)

\end{bubble}

\end{textblock}

\begin{textblock}{5}(12.5,1.9)

\includegraphics[scale=0.05]{../pics/hoare.jpg}\\

\end{textblock}

\end{frame}

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\frametitle{\begin{tabular}{c}\\[1cm]\alert{Questions?}\end{tabular}}

\begin{center}

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\begin{center}

My Scala Office Hours: Thursdays 11 -- 13

\end{center}

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\end{document}

\end{document}

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