--- a/doc-src/TutorialI/Misc/pairs.thy Fri Aug 04 23:02:11 2000 +0200
+++ b/doc-src/TutorialI/Misc/pairs.thy Sun Aug 06 15:26:53 2000 +0200
@@ -1,8 +1,26 @@
(*<*)
theory pairs = Main:;
-term(*>*) "let (x,y) = f z in (y,x)";
+(*>*)
+text{*
+HOL also has pairs: \isa{($a@1$,$a@2$)} is of type \isa{$\tau@1$ *
+ $\tau@2$} provided each $a@i$ is of type $\tau@i$. The components of a pair
+are extracted by \isa{fst} and \isa{snd}: \isa{fst($x$,$y$) = $x$} and
+\isa{snd($x$,$y$) = $y$}. Tuples are simulated by pairs nested to the right:
+\isa{($a@1$,$a@2$,$a@3$)} stands for \isa{($a@1$,($a@2$,$a@3$))} and
+\isa{$\tau@1$ * $\tau@2$ * $\tau@3$} for \isa{$\tau@1$ * ($\tau@2$ *
+ $\tau@3$)}. Therefore we have \isa{fst(snd($a@1$,$a@2$,$a@3$)) = $a@2$}.
+
+It is possible to use (nested) tuples as patterns in abstractions, for
+example \isa{\isasymlambda(x,y,z).x+y+z} and
+\isa{\isasymlambda((x,y),z).x+y+z}.
+In addition to explicit $\lambda$-abstractions, tuple patterns can be used in
+most variable binding constructs. Typical examples are
+\begin{quote}
+@{term"let (x,y) = f z in (y,x)"}\\
+@{term"case xs of [] => 0 | (x,y)#zs => x+y"}
+\end{quote}
+Further important examples are quantifiers and sets (see~\S\ref{quant-pats}).
+*}
(*<*)
-term(*>*) "case xs of [] \\<Rightarrow> 0 | (x,y)#zs \\<Rightarrow> x+y"
-(**)(*<*)
end
(*>*)