110 

   110 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     

   111 \begin{frame}[c]

   112   \frametitle{Discussion Forum}

   113   

   114   \large

   115   ``Since we cant use \code{var}s I was wondering if we could use a stack?''

   116   \bigskip\bigskip\bigskip\bigskip

   117 

   118   \small

   119   My \pcode{collatz} and \pcode{collatz_max} functions are 4 loc each. 

   120 \end{frame}

   121 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   122 

   123 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   124 \begin{frame}[t]

   125   \frametitle{Email: Hate 'val'}

   126   

   127   \mbox{}\\[-22mm]\mbox{}

   128   

   129   \begin{center}

   130     \begin{bubble}[10.5cm]

   131     Subject: \textbf{Hate '\textbf{\texttt{val}}'}\hfill 01:00 AM\medskip\\

   132   

   133     Hello Mr Urban,\medskip\\

   134   

   135     I just wanted to ask, how are we suppose to work

   136     with the completely useless \textbf{\texttt{val}}, that can’t be changed ever? Why is

   137     this rule active at all? I’ve spent 4 hours not thinking on the

   138     coursework, but how to bypass this annoying rule. What’s the whole

   139     point of all these coursework, when we can’t use everything Scala

   140     gives us?!?\medskip\\

   141   

   142     Regards.\\

   143     \mbox{}\hspace{5mm}\textcolor{black!50}{<<deleted>>}\\

   144     \end{bubble}

   145   \end{center}

   146   

   147 \end{frame}

   148 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     

   149   

   150 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   151 \begin{frame}[c]

   152 

   153  \mbox{}\\[-25mm]\mbox{}

   154 

   155 \begin{center}

   156   \begin{bubble}[10.5cm]

   157   Subject: \textbf{Re: Hate '\textbf{\texttt{val}}'}\hfill 01:02 AM\bigskip\bigskip\\

   158 

   159   \textcolor{black!70}{

   160     \textit{\large<<my usual rant about fp\ldots\\ concurrency bla bla\ldots{} better programs

   161     yada>>}}\bigskip\bigskip\bigskip

   162   

   163   PS: What are you trying to do where you desperately want to use \texttt{var}?

   164   \end{bubble}

   165 \end{center}

   166 

   167 \end{frame}

   168 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     

   169 

   170 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   171 \begin{frame}[c,fragile]

   172 

   173 \begin{textblock}{6}(0.5,0.5)

   174 \begin{bubble}[11.5cm]

   175   \small  

   176   Subject: \textbf{Re: Re: Hate '\textbf{\texttt{val}}'}\hfill 01:04 AM\medskip\\

   177 

   178   \textbf{Right now my is\_legal function works fine:}

   179   

   180 \footnotesize\begin{lstlisting}[language=Scala, numbers=none, xleftmargin=-1mm]

   181  def is_legal(dim: Int, path: Path)(x: Pos): Boolean = {

   182    var boolReturn = false

   183    if(x._1 > dim || x._2 > dim || x._1 < 0 || x._2 < 0) {

   184    else { var breakLoop = false

   185           if(path == Nil) { boolReturn = true }

   186           else { for(i <- 0 until path.length) {

   187                     if(breakLoop == false) {

   188                       if(path(i) == x) {

   189                         boolReturn = true

   190                         breakLoop = true

   191                       }

   192                       else { boolReturn = false }

   193                     } else breakLoop

   194             }

   195           }

   196           boolReturn

   197    }

   198 \end{lstlisting}

   199 \end{bubble}

   200 \end{textblock}

   201 

   202 \begin{textblock}{6}(8.2,11.8)

   203 \begin{bubble}[5.5cm]\footnotesize\bf

   204 \ldots{}but I can’t make it work with boolReturn being val. What approach would

   205 you recommend in this case, and is using var in this case justified?

   206 \end{bubble}

   207 \end{textblock}

   208 

   209 \only<2>{

   210 \begin{textblock}{6}(0.3,11.8)

   211   \begin{bubble}[3.1cm]

   212     \textbf{Me:}

   213     \raisebox{-12mm}{\includegraphics[scale=0.08]{../pics/throwup.jpg}}

   214   \end{bubble}

   215 \end{textblock}}

   216 

   217 \end{frame}

   218 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 

   219 

   220 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   221 \begin{frame}[t,fragile]

   222 

   223 \mbox{}\\[-25mm]\mbox{}

   224 

   225 \begin{textblock}{6}(0.5,2)

   226   \begin{bubble}[11.5cm]

   227   Subject: \textbf{Re: Re: Re: Hate '\textbf{\texttt{val}}'}\hfill 01:06 AM\bigskip\\

   228   \small

   229   

   230   OK. So you want to make sure that the \texttt{x}-position is not outside the

   231   board....and furthermore you want to make sure that the \texttt{x}-position

   232   is not yet in the path list. How about something like\bigskip

   233 

   234 \footnotesize\begin{lstlisting}[language=Scala, numbers=none, xleftmargin=-1mm]

   235  def is_legal(dim: Int, path: Path)(x: Pos): Boolean = 

   236    ...<<some board conditions>>... && !path.contains(x)

   237 \end{lstlisting}\bigskip

   238   

   239   \small Does not even contain a \texttt{val}.

   240   \end{bubble}

   241 \end{textblock}

   242 

   243 \begin{textblock}{6}(7,12)

   244 \footnotesize\textcolor{black!50}{(This is all on one line)}

   245 \end{textblock}

   246 

   247 \end{frame}

   248 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     

   249 

   250 

   251 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   252 \begin{frame}[t,fragile]

   253 

   254 \mbox{}\\[-15mm]\mbox{}

   255 

   256 \begin{textblock}{6}(1,3)

   257   \begin{bubble}[10.5cm]

   258     Subject: \textbf{Re: Re: Re: Re: Hate '\textbf{\texttt{val}}'}\hfill 11:02 AM\bigskip\bigskip\\

   259     

   260     THANK YOU! You made me change my coding perspective. Because of you,

   261     I figured out the next one\ldots

   262   \end{bubble}

   263 \end{textblock}

   264 

   265 \only<2>{

   266 \begin{textblock}{6}(0.3,11.8)

   267   \begin{bubble}[3.1cm]

   268     \textbf{Me:}

   269     \raisebox{-12mm}{\includegraphics[scale=0.15]{../pics/happy.jpg}}

   270   \end{bubble}

   271 \end{textblock}}

   272 

   273 \end{frame}

   274 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 

   275 

   276 

   277  

   115 Don't change anything with the templates!\bigskip

   282 Don't change any names or types in the templates!\bigskip

   120 \item \texttt{var} 

   287 \item \code{var} 

   121 \item \texttt{return} 

   288 \item \code{return} 

   125 \end{itemize}\pause\bigskip

   292 \end{itemize}\bigskip\bigskip

   126 

   293 

   127 

   294 I cannot think of a good reason to use stacks.

   128 \mbox{}\hfill\textit{``Scala --- \underline{S}lowly \underline{c}ompiled 

   129 \underline{a}cademic \underline{la}nguage''}\smallskip\\

   130 \mbox{}\hfill\textit{ --- a joke(?) found on Twitter}\bigskip

   131 \end{frame}

   132 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   133 

   134 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   135 \begin{frame}[t]

   136 \frametitle{Email: Hate 'val'}

   137 

   138 \mbox{}\\[-25mm]\mbox{}

   139 

   140 \begin{center}

   141   \begin{bubble}[10.5cm]

   142   Subject: \textbf{Hate '\textbf{\texttt{val}}'}\hfill 01:00 AM\medskip\\

   143 

   144   Hello Mr Urban,\medskip\\

   145 

   146   I just wanted to ask, how are we suppose to work

   147   with the completely useless \textbf{\texttt{val}}, that can’t be changed ever? Why is

   148   this rule active at all? I’ve spent 4 hours not thinking on the

   149   coursework, but how to bypass this annoying rule. What’s the whole

   150   point of all these coursework, when we can’t use everything Scala

   151   gives us?!?\medskip\\

   152 

   153   Regards.\\

   154   \mbox{}\hspace{5mm}\textcolor{black!50}{<<deleted>>}\\

   155   \end{bubble}

   156 \end{center}

   157 

   158 \end{frame}

   159 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     

   160 

   161 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   162 \def\firstcircle{(0,0) circle (1.4cm)}

   163 \def\secondcircle{(0:2cm) circle (1.4cm)}

   164 \colorlet{circle edge}{blue!50}

   165 \colorlet{circle area}{blue!20}

   166 

   167 \tikzset{filled/.style={fill=circle area, draw=circle edge, thick},

   168     outline/.style={draw=circle edge, thick}}

   169 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   170 \begin{frame}[c,fragile]

   171 \frametitle{Par: Intersections}

   172 

   173 \begin{textblock}{6}(1,2)

   174 \begin{tikzpicture}

   175   \draw[outline] \firstcircle node {$A$};

   176   \node[anchor=south] at (current bounding box.north)

   177     {$A = \{1,2,3,\ldots,1000\}$};

   178 \end{tikzpicture}

   179 \end{textblock}

   180 

   181 \begin{textblock}{6}(8,2)

   182 \begin{tikzpicture}

   183   \draw[outline] \secondcircle node {$B$};

   184   \node[anchor=south] at (current bounding box.north)

   185     {$B = \{1,5,9,13,\ldots,997\}$};

   186 \end{tikzpicture}

   187 \end{textblock}

   188 

   189 \begin{textblock}{6}(3.3,9)

   190 \begin{tikzpicture}

   191     \begin{scope}

   192         \clip \firstcircle;

   193         \fill[filled] \secondcircle;

   194     \end{scope}

   195     \draw[outline] \firstcircle node {$A$};

   196     \draw[outline] \secondcircle node {$B$};

   197     \node[anchor=north] at (current bounding box.south)

   198     {How many elements are in $A \cap B$?};

   199 \end{tikzpicture}

   200 \end{textblock}  

   201 

   288 \frametitle{Why Scala? No null!}

   381 \frametitle{Option Type}

   289 

   382 

   290 

   383 

   291 \begin{itemize}

   384   

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

   385 \end{frame}

   293 \end{itemize}

   386 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   294 

   387 

   295 

   388 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     

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

   389 \begin{frame}[t]

   297   \begin{bubble}[10.5cm]\small

   390 \frametitle{Higher-Order Functions}

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

   391   

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

   392   

   300       first comprehensive type system for references in an object

   393     

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

   394 \end{frame}

   302       of references should be absolutely safe, with checking performed

   395 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

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

   396   

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

   305       easy to implement. This has led to innumerable errors,

   306       vulnerabilities, and system crashes, which have probably caused

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

   308       \hfill Sir Tony (Hoare)

   309 \end{bubble}

   310 \end{textblock}

   311   

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

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

   314 \end{textblock}

   315   

   316 \end{frame}

   317 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%