presentation: fix a couple typos I noticed during the talk

presentation/main.tex

@@ -97,7 +97,7 @@
       \begin{lstlisting}
 for (k, v) in db:
     if query(k):
-        res.append(v)
+        res.append((k, v))
 
 return dict(res)
       \end{lstlisting}
@@ -125,7 +125,7 @@ return dict(res)
       \begin{lstlisting}
 for (k, v) in db.iter() {
     if query(k) {
-        res.push(v);
+        res.push((k, v));
     }
 };
 
@@ -721,8 +721,8 @@ eq (1, #"a") (1, #"a")
 let eq$_\tt{int}$ = intEq in
 let eq$_\tt{char}$ = charEq in
 let eq$_{\alpha * \beta}$ = $\lambda$eq$_\alpha$.$\lambda$eq$_\beta$.$\lambda$x.$\lambda$y.
-             (eq (fst x) (fst y)) andalso
-               (eq (snd x) (snd y))
+             (eq$_\alpha$ (fst x) (fst y)) andalso
+               (eq$_\beta$ (snd x) (snd y))
              in
 
 eq$_{\alpha * \beta}$ eq$_\tt{int}$ eq$_\tt{char}$ (1, #"a") (1, #"a")
@@ -1239,7 +1239,7 @@ end
 
 \begin{frame}{Iteration: big payoff!}
   \begin{align*}
-    \tt{for} :: \forall \gamma . \forall iota .&\\
+    \tt{for} :: \forall \gamma . \forall \iota .&\\
       &(\tt{item} ::_i \gamma \bs \tt{item}_\gamma) .\\
       &(\tt{item} ::_i \iota \bs \tt{item}_\iota) .\\
       &(\tt{next} ::_i \gamma \arrow (\tt{item}_\gamma * \gamma) \tt{ option} \bs \tt{next}_\gamma) .\\