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%cheat sheet+
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%http://worldline.github.io/scala-cheatsheet/+
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\begin{document}+
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\section*{Scala in 6CCS3CFL}+
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+
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For the coursework in this module you are free to use any programming+
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language you like, but I will show you all my code using Scala---I hope+
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you have fond memories of Scala from PEP. I will use the current+
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stable version of Scala, which is 2.13.3. If you need a reminder of+
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the Scala handouts for PEP have a look+
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\hr{http://talisker.nms.kcl.ac.uk/cgi-bin/repos.cgi/pep-material/raw-file/tip/handouts/pep-ho.pdf}\bigskip+
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+
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\noindent+
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The main difference to the Scala I showed you in PEP is that in CFL+
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I will use the Ammonite REPL+
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+
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\begin{quote}+
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\url{https://ammonite.io/#Ammonite-REPL}+
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\end{quote}+
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+
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\noindent+
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This is a drop-in replacement for the original Scala REPL and+
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works very similarly, for example+
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+
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\begin{lstlisting}[language={},numbers=none,basicstyle=\ttfamily\small]+
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$ amm+
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Loading...  +
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Welcome to the Ammonite Repl 2.2.0 (Scala 2.13.3 Java 9)+
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scala> 1 + 2 +
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res0: Int = 3+
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\end{lstlisting} %% $+
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+
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\noindent+
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Ammonite uses the same Scala compiler, just adds some useful features+
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on top of it. It is quite main-stream in the Scala community and it should+
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therefore be very easy for you to install \texttt{amm}.  The big+
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advantage of Ammonite is that it comes with some additional libraries+
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already built-in and also allows one to easily break up code into+
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smaller modules. For example reading and writing files in Ammonite can+
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be achieved with+
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+
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\begin{lstlisting}[numbers=none,language=Scala]+
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scala> import ammonite.ops._+
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  +
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scala> read(pwd / "file.name")   +
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res1: String = """..."""+
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+
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scala> write.over(pwd / "file.name", "foo bar")+
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\end{lstlisting}+
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+
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\noindent+
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For loading and accessing code from another Scala file, you can import it+
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as follows:+
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+
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\begin{lstlisting}[numbers=none,language=Scala]+
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import $file.name-of-the-file+
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import name-of-the-file._+
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\end{lstlisting}  %% $+
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+
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\noindent+
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This assumes the other Scala file is called+
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\texttt{name-of-the-file.sc} and requires the file to be in the same+
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directory where \texttt{amm} is working in. This will be very convenient +
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for the compiler we implement in CFL, because it allows us to easily+
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break-up the code into the lexer, parser and code generator.+
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+
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Another feature which exists in Ammonite, but not yet in the+
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current version of Scala (it will be in the next version called dotty)+
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is that you can mark functions as \texttt{@main}. For example+
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+
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\begin{lstlisting}[numbers=none,language=Scala]+
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@main+
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def foo() = ...+
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\end{lstlisting}+
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+
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\noindent+
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This means you can now call that function from the command line like+
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+
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\begin{lstlisting}[numbers=none,language=Scala]+
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$ amm file.sc foo+
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\end{lstlisting} %% $+
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+
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\noindent+
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If you want to specify an argument on the commandline, say an int and+
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a string, then you can write+
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+
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\begin{lstlisting}[numbers=none,language=Scala]+
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@main+
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def bar(i: Int, s: String) = ...+
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\end{lstlisting}+
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+
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\noindent+
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and then call+
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+
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\begin{lstlisting}[numbers=none,language=Scala]+
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$ amm file.sc 42 foobar+
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\end{lstlisting} %% $+
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+
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\noindent+
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What is also good in Ammonite that you can specify more than one+
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function to be ``main'' and then specify on the command line which+
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function do you want to run as entry-point.\bigskip+
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+
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\noindent+
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To sum up, Ammonite is a really useful addition to the Scala ecosystem.+
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You can find more information about how to use it in the first five chapters+
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of the ``Hands-on Scala'' book by Li Haoyi. These chapters are+
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free and can be used as a reference, see:+
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+
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\begin{center}+
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\url{https://www.handsonscala.com/part-i-introduction-to-scala.html}+
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\end{center}+
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+
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\end{document}+
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+
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