X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;ds=sidebyside;f=deliverables%2Fp2%2Fp2.tex;h=a3fca20f9598cffe0fa94e09a6b7311cd79ef977;hb=158fb0cf298aaae42c8460f92bb7d797d5def9bd;hp=0399d8d51fde04146bc252dd7464d802bfc3e08c;hpb=5f216c089cf607cab359f5bc8d5b4ec76bc15a25;p=cc1516.git

diff --git a/deliverables/p2/p2.tex b/deliverables/p2/p2.tex
index 0399d8d..a3fca20 100644
--- a/deliverables/p2/p2.tex
+++ b/deliverables/p2/p2.tex
@@ -67,6 +67,11 @@ sem :: AST -> SemOutput
 	\pause%
 	\begin{block}{Order?}
 		Does matter for variables, not for functions.
+		\pause
+		\begin{itemize}
+			\item Note that this means that \texttt{ones=1:ones} is 
+					not allowed.
+		\end{itemize}
 	\end{block}
 	\pause%
 	\begin{block}{Mutual recursion?}
@@ -74,10 +79,121 @@ sem :: AST -> SemOutput
 	\end{block}
 	\pause%
 	\begin{block}{Higher order functions?}
-		Hopefully in the future
+		Would be an interesting idea for assignment 4
 	\end{block}
 \end{frame}
 
+\begin{frame}[fragile]
+	\frametitle{Mutual Recursion}
+	\begin{itemize}
+		\item Mutual recursion is allowed and type checked, however inference is
+		not complete.
+		\pause
+		\begin{CleanCode}
+flip(n, l) :: Int -> [Int] -> [Int] {
+  if( n <= 0 ) {return l;} 
+  else {return flop(n-1, 0:l);}
+}
+
+flop(n, l) :: Int -> [Int] -> [Int] {
+  return flip(n, 1:l);
+}
+		\end{CleanCode}
+		\pause
+		\item Completely typed specifications are checked correctly.
+	\end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+	\frametitle{Mutual Recursion}
+	\begin{itemize}
+		\item Mutual recursion is allowed and type checked, however inference is
+		not complete.
+		\begin{CleanCode}
+flip(n, l) :: Int -> [Int] -> [Int] {
+  if( n <= 0 ) {return l;} 
+  else {return flop(n-1, 0:l);}
+}
+
+flop(n, l) :: Int -> [Int] -> Bool {
+  return flip(n, 1:l);
+}
+		\end{CleanCode}
+		\pause
+		\item It is also correctly determined that \texttt{Bool} and the return 
+		type of \texttt{flop(n,l)} don't match.
+	\end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+	\frametitle{Mutual Recursion}
+	\begin{itemize}
+		\item Mutual recursion is allowed and type checked, however inference is
+		not complete.
+		\begin{CleanCode}
+flip(n, l) {
+  if( n <= 0 ) {return l;} 
+  else {return flop(n-1, 0:l);}
+}
+
+flop(n, l) {
+  return flip(n, 1:l);
+}
+		\end{CleanCode}
+	\end{itemize}
+\end{frame}
+
+
+\begin{frame}[fragile]
+	\frametitle{Mutual Recursion}
+	\begin{itemize}
+		\item Mutual recursion is allowed and type checked, however inference is
+		not complete.
+		\begin{CleanCode}
+flip(n, l) :: Int -> [Int] -> vTqhp {
+  if( n <= 0 ) {return l;} 
+  else {return flop(n-1, 0:l);}
+}
+
+flop(n, l) :: Int -> [Int] -> HSWdn {
+  return flip(n, 1:l);
+}
+		\end{CleanCode}
+		\item However when no type information is given at all our algorithm 
+		fails to correctly infer the result type of the two function.
+	\end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+	\frametitle{But wait, there is more!}
+	\framesubtitle{Trouble that is}
+	\begin{itemize}
+		\item Polymorphism is not working great either.
+		\begin{CleanCode}
+id(x) :: a -> a {
+    return x;    
+}
+		\end{CleanCode}
+		\pause
+		\item Is typed fun, but when we introduce: 
+		\begin{CleanCode}
+var x = id(5);
+var y = id(True);
+		\end{CleanCode}
+		\pause
+		\begin{CleanCode}
+2:12 SemError: Cannot unify types. Expected: Int. Given: Bool
+		\end{CleanCode}
+	\end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+	\frametitle{But wait, there is more!}
+	\framesubtitle{Trouble that is}
+	
+	\begin
+\end{frame}
+
 % - Can functions that are defined later in a file call earlier defined functions?
 % - Can local variables be defined in terms of other local variables?
 % - How do you deal with assignments?