diff -r bb2335a5ca58 -r e93a9e74ca8e coursework/cw03.tex
--- a/coursework/cw03.tex	Mon Aug 31 18:15:12 2020 +0100
+++ b/coursework/cw03.tex	Tue Sep 01 12:44:07 2020 +0100
@@ -7,11 +7,9 @@
 
 \section*{Coursework 3}
 
-TODO: Testcases for expressions
-\url{https://github.com/ArashPartow/math-parser-benchmark-project}
 
 
-\noindent This coursework is worth 5\% and is due on \cwTHREE{} at
+\noindent This coursework is worth 10\% and is due on \cwTHREE{} at
 18:00. You are asked to implement a parser for the WHILE language and
 also an interpreter. You can do the implementation in any programming
 language you like, but you need to submit the source code with which
@@ -20,13 +18,13 @@
 parser.  Please package everything(!) in a zip-file that creates a
 directory with the name \texttt{YournameYourFamilyname} on my end.
 
-\subsection*{Disclaimer}
+\subsection*{Disclaimer\alert}
 
-It should be understood that the work you submit represents
-your own effort. You have not copied from anyone else. An
-exception is the Scala code I showed during the lectures,
-which you can use. You can also use your own code from the
-CW~1 and CW~2.
+It should be understood that the work you submit represents your own
+effort. You have not copied from anyone else. An exception is the
+Scala code I showed during the lectures or uploaded to KEATS, which
+you can both use. You can also use your own code from the CW~1 and
+CW~2.
 
 
 \subsection*{Question 1}
@@ -54,22 +52,21 @@
 
 You should implement a parser for the WHILE language using parser
 combinators. Be careful that the parser takes as input a stream, or
-list, of tokens generated by the tokenizer from the previous
+list, of \emph{tokens} generated by the tokenizer from the previous
 coursework. For this you might want to filter out whitespaces and
 comments. Your parser should be able to handle the WHILE programs in
-Figures~\ref{fib}, \ref{loop} and \ref{primes} (if your lexer cannot
-deal with comments you can delete them from the prime number program).
-In addition give the parse tree for the statement:
+Figures~\ref{fib}, \ref{loop} and \ref{primes}.  In addition give the
+parse tree for the statement:
 
 \begin{lstlisting}[language=While,numbers=none]
 if (a < b) then skip else a := a * b + 1
 \end{lstlisting}
 
 \noindent
-A (possibly incomplete) datatype for parse trees in Scala would
-look as in Figure~\ref{trees}.
+A (possibly incomplete) datatype for parse trees in Scala is shown
+in Figure~\ref{trees}.
 
-\begin{figure}
+\begin{figure}[p]
 \begin{lstlisting}[language=Scala]
 abstract class Stmt
 abstract class AExp
@@ -81,6 +78,10 @@
 case class If(a: BExp, bl1: Block, bl2: Block) extends Stmt
 case class While(b: BExp, bl: Block) extends Stmt
 case class Assign(s: String, a: AExp) extends Stmt
+case class Read(s: String) extends Stmt
+case class WriteVar(s: String) extends Stmt  
+case class WriteStr(s: String) extends Stmt 
+                      // for printing variables and strings
 
 case class Var(s: String) extends AExp
 case class Num(i: Int) extends AExp
@@ -90,6 +91,7 @@
 case object False extends BExp
 case class Bop(o: String, a1: AExp, a2: AExp) extends BExp
 case class Lop(o: String, b1: BExp, b2: BExp) extends BExp
+                     // logical operations: and, or
 \end{lstlisting}
 \caption{The datatype for parse trees in Scala.\label{trees}}
 \end{figure}
@@ -124,7 +126,8 @@
 if-statement will ``run'' the if-branch if the boolean
 evaluates to \pcode{true}, otherwise the else-branch.
 Loops should be run as long as the boolean is \pcode{true}.
-
+Programs you should be able to run are shown in
+Figures \ref{fib} -- \ref{collatz}.
 
 
 Give some time measurements for your interpreter
@@ -134,20 +137,26 @@
 you scale this value if you are willing to wait, say
 1 Minute?
 
-\begin{figure}[p]
-\lstinputlisting[language=while,xleftmargin=20mm]{../progs/fib.while}
+\begin{figure}[h]
+\lstinputlisting[language=while,xleftmargin=20mm]{../progs/while-tests/fib.while}
 \caption{Fibonacci program in the WHILE language.\label{fib}}
 \end{figure}
 
-\begin{figure}[p]
-\lstinputlisting[language=while,xleftmargin=20mm]{../progs/loops.while}
+\begin{figure}[h]
+\lstinputlisting[language=while,xleftmargin=20mm]{../progs/while-tests/loops.while}
 \caption{The three-nested-loops program in the WHILE language. 
 Usually used for timing measurements.\label{loop}}
 \end{figure}
 
+\begin{figure}[h]
+\lstinputlisting[language=while,xleftmargin=0mm]{../progs/while-tests/primes.while}
+\caption{Prime number program.\label{primes}}
+\end{figure}
+
+
 \begin{figure}[p]
-\lstinputlisting[language=while,xleftmargin=0mm]{../progs/primes.while}
-\caption{Prime number program.\label{primes}}
+\lstinputlisting[language=while,xleftmargin=0mm]{../progs/while-tests/collatz2.while}
+\caption{Collatz series program.\label{collatz}}
 \end{figure}
 
 \end{document}