\begin{document}
\frame{\titlepage}
- %- Anything that is specific to your parser
- % - Positions Pim
- % - yard (parser combinators) Pim
- % - Implementation language Pim
- % - Elaborate diffulties and eases (Tussendoor)
- % - LL* Mart
- %- Did you split it into two phases lexing and parsing, or just one phase? Pim
- % - Why parser combinator for lexer
- %- Did you change the grammar, and if so how? Mart
- % - Standard tricks, remove left assoc, get operator assoc correct.
- % - How did you solve the problems of precedence and associativity?
- %- Does your parser stop after the first encountered error or can it go on? Pim
- % (bij Yard erin fietsen)
- % - Stops, this is design, parsing should be correct!!!1!
- %- For a couple of example programs, when you do a sequence of Mart
- % 1. parse
- % 2. pretty-print
- % 3. parse
- % 4. pretty-print
- % -- Dit gaan we met een shell scriptje doen
- %- Code metrics, loc, etc, met stomme xkcd Mart
- % How many lines of code do you have, how many hours did you work on it?
- % “Measuring programming progress by lines of code is like measuring
- % aircraft building progress by weight.”
- %
- % ― Bill Gates
- % Hoeveel uur, ook geen idee. Ook een stomme quote
- %- Did you try your parser on weird inputs, like 100 megabyte of nested Mart
- %parenthesis? 1 gigabyte?
- % - Yes, we did, didn't work out. Uses big heap and stack
- %- Problems and learned things
- %- Demonstrate your parser and pretty-printer on two or three programs that you
- % find interesting Mart (teminaldingen kun jij goed ;))
+ \section{Introduction}
+ \begin{frame}
+ \frametitle{\textsc{SPL}}
+ \framesubtitle{Acronym for: \textsc{SPL}: Parser and Lexer}
+ \begin{block}{Features}
+ \begin{itemize}
+ \item Implementation language:
+ Clean ({\tiny\url{http://clean.cs.ru.nl}})
+ \pause
+ \begin{itemize}
+ \item Pure language
+ \item Higher order functions
+ \item Monads
+ \item Using parser combinator library \textsc{Yard}
+ \end{itemize}
+ \pause
+ \item Positional data available for easy locating of errors.
+ \pause
+ \item Standardized parser errors. This means you can set it as
+ \texttt{buildprg} in \texttt{vim} and you can then use the
+ quickfix window!
+ \end{itemize}
+ \end{block}
+ \end{frame}
+
+ \begin{frame}[fragile]
+ \frametitle{\textsc{YARD}}
+ \framesubtitle{A minimal home grown monadic parser combinator library}
+ \begin{itemize}
+ \item Inspired by \textsc{parsec}: $1pc=3.375\cdot10^{16}yd$~\footnote{
+ A yard is exactly $36$ inch and an inch is exactly the length
+ of $3$ barleycorns}.
+ \item Definitons:
- \begin{lstlisting}
++ \begin{CleanCode}
+ :: Error = PositionalError Int Int String | Error String
+ :: Parser a b = Parser ([a] -> (Either Error b, [a]))
- \end{lstlisting}
++ \end{CleanCode}
+ \pause
+ \item Matches longest left-most parser
+ \pause
+ \item Stops immediately on error\pause\\
+ By design!
+ \end{itemize}
+ \end{frame}
+
+ \begin{frame}[fragile]
+ \frametitle{\textsc{YARD} Combinators}
- \begin{lstlisting}
++ \begin{CleanCode}
+ instance Functor (Parser a)
+ instance Applicative (Parser a)
+ instance Monad (Parser a)
+ instance Alternative (Parser a)
+
+ runParser :: (Parser a b) [a] -> (Either Error b, [a])
+ (<?>) :: (Parser a b) Error -> Parser a b
+ fail :: Parser a b
+ top :: Parser a a
+ peek :: Parser a a
+ satisfy :: (a -> Bool) -> Parser a a
+ check :: (a -> Bool) -> Parser a a
+ (until) infix 2 :: (Parser a b) (Parser a c) -> Parser a [b]
+ item :: a -> Parser a a | Eq a
+ list :: [a] -> Parser a [a] | Eq a
+ eof :: Parser a Void
- \end{lstlisting}
++ \end{CleanCode}
+ \end{frame}
+
+ \section{Design choices}
+ \begin{frame}
+ \frametitle{Adapting the grammar}
+ \begin{itemize}
+ \item Remove left recursion
+ \item Fixing associativity
+ \item Added small features such as escape characters \texttt{
+ \textbackslash n\textbackslash b}
+ \pause
+ \item Show grammar now\ldots
+ \end{itemize}
+ \end{frame}
+
+ \begin{frame}
+ \frametitle{Two-phase design}
+ \framesubtitle{Lexing}
+ Also done with \textsc{YARD} because
+ \begin{itemize}
+ \item Multiline comments
+ \item Alternatives
+ \item Positions
+ \end{itemize}
+ \end{frame}
+
+ \begin{frame}[fragile]
+ \frametitle{Two-phase design}
+ \framesubtitle{Parsing}
+ Read from stdin, write to stdout\\
+ Added some handy primitives
- \begin{lstlisting}
++ \begin{CleanCode}
+ parseBlock :: Parser Token [Stmt]
+
+ parseOpR :: (Parser Token Op2) (Parser Token Expr) -> Parser Token Expr
+ parseOpL :: (Parser Token Op2) (Parser Token Expr) -> Parser Token Expr
+
+ trans2 :: TokenValue (TokenValue -> a) -> Parser Token a
+ trans1 :: TokenValue a -> Parser Token a
+
+ peekPos :: Parser Token Pos
- \end{lstlisting}
++ \end{CleanCode}
+ \end{frame}
+
+ \begin{frame}[fragile]
+ \frametitle{Statistics}
+ \framesubtitle{Lines of code}
+ \lstinputlisting{|"wc -l ../../*.[di]cl"}
+ \pause
+ \begin{block}{}
+ \emph{``Measuring programming progress by lines of code is like
+ measuring aircraft building progress by weight.''}\\
+ {---} Bill Gates
+ \end{block}
+ \end{frame}
+
+ \begin{frame}
+ \frametitle{Statistics}
+ \framesubtitle{Hours of work}
+ We have no clue how much time we have worked on it\ldots
+ \pause
+ \begin{block}{}
+ \emph{``Choose a job you love, and you will never have to work a day in
+ your life.''}\\
+ {---} Confucius
+ \end{block}
+ \end{frame}
+
+ \section{Examples}
+ \begin{frame}
+ \frametitle{Weird inputs}
+ \begin{itemize}
+ \item \pause Heap full
+ \pause\ldots Increase heap\\
+ \texttt{\$ ./spl -h 2000M}
+ \item \pause Stack full
+ \pause\ldots Increase stack\\
+ \texttt{\$ ./spl -s 200M}
+ \item \pause Segmentation fault
+ \pause\ldots Enable memory overcommitting\\
+ \texttt{\# echo 1 > /proc/sys/vm/overcommit\_memory}
+ \item \pause Still segmentation fault
+ \pause\ldots Buy more \textsc{RAM}
+ \item \pause Still segmentation fault?
+ \pause\ldots Divide into modules and parse separatly~\footnote{To be
+ implemented}
+ \item \pause Thus, we are only limited by hardware\ldots
+ \end{itemize}
+ \end{frame}
+
+ \begin{frame}
+ \frametitle{Learned lessons}
+ \begin{itemize}
+ \item \pause Parser combinators are elegant!
+ \item \pause Positional errors are a must!
+ \item \ldots
+ \end{itemize}
+ \end{frame}
\end{document}
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