worksheet.tex

% !TEX root = main.tex
\documentclass[11pt, a4paper]{article}
\input{preamble}

\begin{document}

  % Top matter.
  \title{Tutorial Worksheet 1}
  \author{Duncan Paul Attard}
  \date{\today}
  \maketitle

  \begin{center}
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  \end{center}

  \section{Installing Erlang}

  The pre-built Erlang package for your operating system can be downloaded from \href{https://www.erlang-solutions.com/resources/download.html}{Erlang Solutions}.

  \section{Testing the Erlang shell}

  To confirm that Erlang has been successfully installed, we can try to invoke its shell.
  This can be done by typing \texttt{erl} in your operating system's terminal.
  You should get something that looks similar to the following:

\begin{lstlisting}[language=bash]
duncan@term:/example$ erl

Erlang/OTP 18 [erts-7.2] [source] [smp:4:4] [async-threads:10] [kernel-poll:false]
Eshell V7.2  (abort with ^G)
1> _
\end{lstlisting}

  Type \texttt{1 + 1.} followed by enter.
  What happens?
  Try out other arithmetic expressions for yourself.
  When ready, quit the Erlang shell by typing \texttt{q().}

  \begin{block}{Shell expressions}
    Erlang expressions entered in the shell \emph{must} terminate with the period symbol `\texttt{.}'.
    Issuing enter without typing in `\texttt{.}' gives us the opportunity to type in code that can extend over multiple lines (\eg a lengthy function).
    Code spanning multiple lines can then be terminated accordingly by typing `\texttt{.}'.

    \medskip
    To recall the latest executed shell command, tap the \emph{up} arrow key on your keyboard.
  \end{block}

\begin{assignment}

  \section{Fibonacci numbers}

  Write a recursive function \texttt{fib(N)} that calculates the fibonacci number for a given non-negative number (\ie $n \geq 0$).
  Try to run your function using very large numbers and observe what happens.

  \section{Fibonacci numbers revisited}

  Why do you think the \texttt{fib(N)} did not perform as well as expected when tested with large numbers?

  \medskip
  Implement a new tail-recursive function \texttt{fib2(N)} that calculates the fibonacci number using \emph{two} accumulator values to store the values for $n - 1$ and $n - 2$. The following snippet should act as a scaffolding for your work.

\begin{lstlisting}{language=erlang}
fib2(N) -> fib2(N, 1, 0).
fib2(0, (*@\textit{Nminus1}@*), (*@\textit{Nminus2}@*)) ->
  % Base case implementation.
  ok;
fib2(N, (*@\textit{Nminus1}@*), (*@\textit{Nminus2}@*)) ->
  % Recursive case implementation.
  ok.
\end{lstlisting}

\end{assignment}

\end{document}