
diff -r 3a1aef73b2b2 -r aea5d7fa7ef5 doc-src/Classes/Thy/document/Classes.tex
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+++ b/doc-src/Classes/Thy/document/Classes.tex	Wed Mar 04 11:05:29 2009 +0100
@@ -0,0 +1,1335 @@
+%
+\begin{isabellebody}%
+\def\isabellecontext{Classes}%
+%
+\isadelimtheory
+%
+\endisadelimtheory
+%
+\isatagtheory
+\isacommand{theory}\isamarkupfalse%
+\ Classes\isanewline
+\isakeyword{imports}\ Main\ Setup\isanewline
+\isakeyword{begin}%
+\endisatagtheory
+{\isafoldtheory}%
+%
+\isadelimtheory
+%
+\endisadelimtheory
+%
+\isamarkupsection{Introduction%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+Type classes were introduces by Wadler and Blott \cite{wadler89how}
+  into the Haskell language, to allow for a reasonable implementation
+  of overloading\footnote{throughout this tutorial, we are referring
+  to classical Haskell 1.0 type classes, not considering
+  later additions in expressiveness}.
+  As a canonical example, a polymorphic equality function
+  \isa{eq\ {\isasymColon}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ bool} which is overloaded on different
+  types for \isa{{\isasymalpha}}, which is achieved by splitting introduction
+  of the \isa{eq} function from its overloaded definitions by means
+  of \isa{class} and \isa{instance} declarations:
+  \footnote{syntax here is a kind of isabellized Haskell}
+
+  \begin{quote}
+
+  \noindent\isa{class\ eq\ where} \\
+  \hspace*{2ex}\isa{eq\ {\isasymColon}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ bool}
+
+  \medskip\noindent\isa{instance\ nat\ {\isasymColon}\ eq\ where} \\
+  \hspace*{2ex}\isa{eq\ {\isadigit{0}}\ {\isadigit{0}}\ {\isacharequal}\ True} \\
+  \hspace*{2ex}\isa{eq\ {\isadigit{0}}\ {\isacharunderscore}\ {\isacharequal}\ False} \\
+  \hspace*{2ex}\isa{eq\ {\isacharunderscore}\ {\isadigit{0}}\ {\isacharequal}\ False} \\
+  \hspace*{2ex}\isa{eq\ {\isacharparenleft}Suc\ n{\isacharparenright}\ {\isacharparenleft}Suc\ m{\isacharparenright}\ {\isacharequal}\ eq\ n\ m}
+
+  \medskip\noindent\isa{instance\ {\isacharparenleft}{\isasymalpha}{\isasymColon}eq{\isacharcomma}\ {\isasymbeta}{\isasymColon}eq{\isacharparenright}\ pair\ {\isasymColon}\ eq\ where} \\
+  \hspace*{2ex}\isa{eq\ {\isacharparenleft}x{\isadigit{1}}{\isacharcomma}\ y{\isadigit{1}}{\isacharparenright}\ {\isacharparenleft}x{\isadigit{2}}{\isacharcomma}\ y{\isadigit{2}}{\isacharparenright}\ {\isacharequal}\ eq\ x{\isadigit{1}}\ x{\isadigit{2}}\ {\isasymand}\ eq\ y{\isadigit{1}}\ y{\isadigit{2}}}
+
+  \medskip\noindent\isa{class\ ord\ extends\ eq\ where} \\
+  \hspace*{2ex}\isa{less{\isacharunderscore}eq\ {\isasymColon}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ bool} \\
+  \hspace*{2ex}\isa{less\ {\isasymColon}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ bool}
+
+  \end{quote}
+
+  \noindent Type variables are annotated with (finitely many) classes;
+  these annotations are assertions that a particular polymorphic type
+  provides definitions for overloaded functions.
+
+  Indeed, type classes not only allow for simple overloading
+  but form a generic calculus, an instance of order-sorted
+  algebra \cite{Nipkow-Prehofer:1993,nipkow-sorts93,Wenzel:1997:TPHOL}.
+
+  From a software engeneering point of view, type classes
+  roughly correspond to interfaces in object-oriented languages like Java;
+  so, it is naturally desirable that type classes do not only
+  provide functions (class parameters) but also state specifications
+  implementations must obey.  For example, the \isa{class\ eq}
+  above could be given the following specification, demanding that
+  \isa{class\ eq} is an equivalence relation obeying reflexivity,
+  symmetry and transitivity:
+
+  \begin{quote}
+
+  \noindent\isa{class\ eq\ where} \\
+  \hspace*{2ex}\isa{eq\ {\isasymColon}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ bool} \\
+  \isa{satisfying} \\
+  \hspace*{2ex}\isa{refl{\isacharcolon}\ eq\ x\ x} \\
+  \hspace*{2ex}\isa{sym{\isacharcolon}\ eq\ x\ y\ {\isasymlongleftrightarrow}\ eq\ x\ y} \\
+  \hspace*{2ex}\isa{trans{\isacharcolon}\ eq\ x\ y\ {\isasymand}\ eq\ y\ z\ {\isasymlongrightarrow}\ eq\ x\ z}
+
+  \end{quote}
+
+  \noindent From a theoretic point of view, type classes are lightweight
+  modules; Haskell type classes may be emulated by
+  SML functors \cite{classes_modules}. 
+  Isabelle/Isar offers a discipline of type classes which brings
+  all those aspects together:
+
+  \begin{enumerate}
+    \item specifying abstract parameters together with
+       corresponding specifications,
+    \item instantiating those abstract parameters by a particular
+       type
+    \item in connection with a ``less ad-hoc'' approach to overloading,
+    \item with a direct link to the Isabelle module system
+      (aka locales \cite{kammueller-locales}).
+  \end{enumerate}
+
+  \noindent Isar type classes also directly support code generation
+  in a Haskell like fashion.
+
+  This tutorial demonstrates common elements of structured specifications
+  and abstract reasoning with type classes by the algebraic hierarchy of
+  semigroups, monoids and groups.  Our background theory is that of
+  Isabelle/HOL \cite{isa-tutorial}, for which some
+  familiarity is assumed.
+
+  Here we merely present the look-and-feel for end users.
+  Internally, those are mapped to more primitive Isabelle concepts.
+  See \cite{Haftmann-Wenzel:2006:classes} for more detail.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsection{A simple algebra example \label{sec:example}%
+}
+\isamarkuptrue%
+%
+\isamarkupsubsection{Class definition%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+Depending on an arbitrary type \isa{{\isasymalpha}}, class \isa{semigroup} introduces a binary operator \isa{{\isacharparenleft}{\isasymotimes}{\isacharparenright}} that is
+  assumed to be associative:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{class}\isamarkupfalse%
+\ semigroup\ {\isacharequal}\isanewline
+\ \ \isakeyword{fixes}\ mult\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}\ \ \ \ {\isacharparenleft}\isakeyword{infixl}\ {\isachardoublequoteopen}{\isasymotimes}{\isachardoublequoteclose}\ {\isadigit{7}}{\isadigit{0}}{\isacharparenright}\isanewline
+\ \ \isakeyword{assumes}\ assoc{\isacharcolon}\ {\isachardoublequoteopen}{\isacharparenleft}x\ {\isasymotimes}\ y{\isacharparenright}\ {\isasymotimes}\ z\ {\isacharequal}\ x\ {\isasymotimes}\ {\isacharparenleft}y\ {\isasymotimes}\ z{\isacharparenright}{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent This \hyperlink{command.class}{\mbox{\isa{\isacommand{class}}}} specification consists of two
+  parts: the \qn{operational} part names the class parameter
+  (\hyperlink{element.fixes}{\mbox{\isa{\isakeyword{fixes}}}}), the \qn{logical} part specifies properties on them
+  (\hyperlink{element.assumes}{\mbox{\isa{\isakeyword{assumes}}}}).  The local \hyperlink{element.fixes}{\mbox{\isa{\isakeyword{fixes}}}} and
+  \hyperlink{element.assumes}{\mbox{\isa{\isakeyword{assumes}}}} are lifted to the theory toplevel,
+  yielding the global
+  parameter \isa{{\isachardoublequote}mult\ {\isasymColon}\ {\isasymalpha}{\isasymColon}semigroup\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequote}} and the
+  global theorem \hyperlink{fact.semigroup.assoc:}{\mbox{\isa{semigroup{\isachardot}assoc{\isacharcolon}}}}~\isa{{\isachardoublequote}{\isasymAnd}x\ y\ z\ {\isasymColon}\ {\isasymalpha}{\isasymColon}semigroup{\isachardot}\ {\isacharparenleft}x\ {\isasymotimes}\ y{\isacharparenright}\ {\isasymotimes}\ z\ {\isacharequal}\ x\ {\isasymotimes}\ {\isacharparenleft}y\ {\isasymotimes}\ z{\isacharparenright}{\isachardoublequote}}.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsubsection{Class instantiation \label{sec:class_inst}%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+The concrete type \isa{int} is made a \isa{semigroup}
+  instance by providing a suitable definition for the class parameter
+  \isa{{\isacharparenleft}{\isasymotimes}{\isacharparenright}} and a proof for the specification of \hyperlink{fact.assoc}{\mbox{\isa{assoc}}}.
+  This is accomplished by the \hyperlink{command.instantiation}{\mbox{\isa{\isacommand{instantiation}}}} target:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{instantiation}\isamarkupfalse%
+\ int\ {\isacharcolon}{\isacharcolon}\ semigroup\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{definition}\isamarkupfalse%
+\isanewline
+\ \ mult{\isacharunderscore}int{\isacharunderscore}def{\isacharcolon}\ {\isachardoublequoteopen}i\ {\isasymotimes}\ j\ {\isacharequal}\ i\ {\isacharplus}\ {\isacharparenleft}j{\isasymColon}int{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ i\ j\ k\ {\isacharcolon}{\isacharcolon}\ int\ \isacommand{have}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isacharparenleft}i\ {\isacharplus}\ j{\isacharparenright}\ {\isacharplus}\ k\ {\isacharequal}\ i\ {\isacharplus}\ {\isacharparenleft}j\ {\isacharplus}\ k{\isacharparenright}{\isachardoublequoteclose}\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\ \ \isacommand{then}\isamarkupfalse%
+\ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isacharparenleft}i\ {\isasymotimes}\ j{\isacharparenright}\ {\isasymotimes}\ k\ {\isacharequal}\ i\ {\isasymotimes}\ {\isacharparenleft}j\ {\isasymotimes}\ k{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ mult{\isacharunderscore}int{\isacharunderscore}def\ \isacommand{{\isachardot}}\isamarkupfalse%
+\isanewline
+\isacommand{qed}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent \hyperlink{command.instantiation}{\mbox{\isa{\isacommand{instantiation}}}} allows to define class parameters
+  at a particular instance using common specification tools (here,
+  \hyperlink{command.definition}{\mbox{\isa{\isacommand{definition}}}}).  The concluding \hyperlink{command.instance}{\mbox{\isa{\isacommand{instance}}}}
+  opens a proof that the given parameters actually conform
+  to the class specification.  Note that the first proof step
+  is the \hyperlink{method.default}{\mbox{\isa{default}}} method,
+  which for such instance proofs maps to the \hyperlink{method.intro-classes}{\mbox{\isa{intro{\isacharunderscore}classes}}} method.
+  This boils down an instance judgement to the relevant primitive
+  proof goals and should conveniently always be the first method applied
+  in an instantiation proof.
+
+  From now on, the type-checker will consider \isa{int}
+  as a \isa{semigroup} automatically, i.e.\ any general results
+  are immediately available on concrete instances.
+
+  \medskip Another instance of \isa{semigroup} are the natural numbers:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{instantiation}\isamarkupfalse%
+\ nat\ {\isacharcolon}{\isacharcolon}\ semigroup\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{primrec}\isamarkupfalse%
+\ mult{\isacharunderscore}nat\ \isakeyword{where}\isanewline
+\ \ {\isachardoublequoteopen}{\isacharparenleft}{\isadigit{0}}{\isasymColon}nat{\isacharparenright}\ {\isasymotimes}\ n\ {\isacharequal}\ n{\isachardoublequoteclose}\isanewline
+\ \ {\isacharbar}\ {\isachardoublequoteopen}Suc\ m\ {\isasymotimes}\ n\ {\isacharequal}\ Suc\ {\isacharparenleft}m\ {\isasymotimes}\ n{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ m\ n\ q\ {\isacharcolon}{\isacharcolon}\ nat\ \isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}m\ {\isasymotimes}\ n\ {\isasymotimes}\ q\ {\isacharequal}\ m\ {\isasymotimes}\ {\isacharparenleft}n\ {\isasymotimes}\ q{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{by}\isamarkupfalse%
+\ {\isacharparenleft}induct\ m{\isacharparenright}\ auto\isanewline
+\isacommand{qed}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent Note the occurence of the name \isa{mult{\isacharunderscore}nat}
+  in the primrec declaration;  by default, the local name of
+  a class operation \isa{f} to instantiate on type constructor
+  \isa{{\isasymkappa}} are mangled as \isa{f{\isacharunderscore}{\isasymkappa}}.  In case of uncertainty,
+  these names may be inspected using the \hyperlink{command.print-context}{\mbox{\isa{\isacommand{print{\isacharunderscore}context}}}} command
+  or the corresponding ProofGeneral button.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsubsection{Lifting and parametric types%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+Overloaded definitions giving on class instantiation
+  may include recursion over the syntactic structure of types.
+  As a canonical example, we model product semigroups
+  using our simple algebra:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{instantiation}\isamarkupfalse%
+\ {\isacharasterisk}\ {\isacharcolon}{\isacharcolon}\ {\isacharparenleft}semigroup{\isacharcomma}\ semigroup{\isacharparenright}\ semigroup\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{definition}\isamarkupfalse%
+\isanewline
+\ \ mult{\isacharunderscore}prod{\isacharunderscore}def{\isacharcolon}\ {\isachardoublequoteopen}p\isactrlisub {\isadigit{1}}\ {\isasymotimes}\ p\isactrlisub {\isadigit{2}}\ {\isacharequal}\ {\isacharparenleft}fst\ p\isactrlisub {\isadigit{1}}\ {\isasymotimes}\ fst\ p\isactrlisub {\isadigit{2}}{\isacharcomma}\ snd\ p\isactrlisub {\isadigit{1}}\ {\isasymotimes}\ snd\ p\isactrlisub {\isadigit{2}}{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ p\isactrlisub {\isadigit{1}}\ p\isactrlisub {\isadigit{2}}\ p\isactrlisub {\isadigit{3}}\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}{\isasymColon}semigroup\ {\isasymtimes}\ {\isasymbeta}{\isasymColon}semigroup{\isachardoublequoteclose}\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}p\isactrlisub {\isadigit{1}}\ {\isasymotimes}\ p\isactrlisub {\isadigit{2}}\ {\isasymotimes}\ p\isactrlisub {\isadigit{3}}\ {\isacharequal}\ p\isactrlisub {\isadigit{1}}\ {\isasymotimes}\ {\isacharparenleft}p\isactrlisub {\isadigit{2}}\ {\isasymotimes}\ p\isactrlisub {\isadigit{3}}{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ mult{\isacharunderscore}prod{\isacharunderscore}def\ \isacommand{by}\isamarkupfalse%
+\ {\isacharparenleft}simp\ add{\isacharcolon}\ assoc{\isacharparenright}\isanewline
+\isacommand{qed}\isamarkupfalse%
+\ \ \ \ \ \ \isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent Associativity from product semigroups is
+  established using
+  the definition of \isa{{\isacharparenleft}{\isasymotimes}{\isacharparenright}} on products and the hypothetical
+  associativity of the type components;  these hypotheses
+  are facts due to the \isa{semigroup} constraints imposed
+  on the type components by the \hyperlink{command.instance}{\mbox{\isa{\isacommand{instance}}}} proposition.
+  Indeed, this pattern often occurs with parametric types
+  and type classes.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsubsection{Subclassing%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+We define a subclass \isa{monoidl} (a semigroup with a left-hand neutral)
+  by extending \isa{semigroup}
+  with one additional parameter \isa{neutral} together
+  with its property:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{class}\isamarkupfalse%
+\ monoidl\ {\isacharequal}\ semigroup\ {\isacharplus}\isanewline
+\ \ \isakeyword{fixes}\ neutral\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}{\isachardoublequoteclose}\ {\isacharparenleft}{\isachardoublequoteopen}{\isasymone}{\isachardoublequoteclose}{\isacharparenright}\isanewline
+\ \ \isakeyword{assumes}\ neutl{\isacharcolon}\ {\isachardoublequoteopen}{\isasymone}\ {\isasymotimes}\ x\ {\isacharequal}\ x{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent Again, we prove some instances, by
+  providing suitable parameter definitions and proofs for the
+  additional specifications.  Observe that instantiations
+  for types with the same arity may be simultaneous:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{instantiation}\isamarkupfalse%
+\ nat\ \isakeyword{and}\ int\ {\isacharcolon}{\isacharcolon}\ monoidl\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{definition}\isamarkupfalse%
+\isanewline
+\ \ neutral{\isacharunderscore}nat{\isacharunderscore}def{\isacharcolon}\ {\isachardoublequoteopen}{\isasymone}\ {\isacharequal}\ {\isacharparenleft}{\isadigit{0}}{\isasymColon}nat{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{definition}\isamarkupfalse%
+\isanewline
+\ \ neutral{\isacharunderscore}int{\isacharunderscore}def{\isacharcolon}\ {\isachardoublequoteopen}{\isasymone}\ {\isacharequal}\ {\isacharparenleft}{\isadigit{0}}{\isasymColon}int{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ n\ {\isacharcolon}{\isacharcolon}\ nat\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isasymone}\ {\isasymotimes}\ n\ {\isacharequal}\ n{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ neutral{\isacharunderscore}nat{\isacharunderscore}def\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\isacommand{next}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ k\ {\isacharcolon}{\isacharcolon}\ int\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isasymone}\ {\isasymotimes}\ k\ {\isacharequal}\ k{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ neutral{\isacharunderscore}int{\isacharunderscore}def\ mult{\isacharunderscore}int{\isacharunderscore}def\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\isacommand{qed}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{instantiation}\isamarkupfalse%
+\ {\isacharasterisk}\ {\isacharcolon}{\isacharcolon}\ {\isacharparenleft}monoidl{\isacharcomma}\ monoidl{\isacharparenright}\ monoidl\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{definition}\isamarkupfalse%
+\isanewline
+\ \ neutral{\isacharunderscore}prod{\isacharunderscore}def{\isacharcolon}\ {\isachardoublequoteopen}{\isasymone}\ {\isacharequal}\ {\isacharparenleft}{\isasymone}{\isacharcomma}\ {\isasymone}{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ p\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}{\isasymColon}monoidl\ {\isasymtimes}\ {\isasymbeta}{\isasymColon}monoidl{\isachardoublequoteclose}\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isasymone}\ {\isasymotimes}\ p\ {\isacharequal}\ p{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ neutral{\isacharunderscore}prod{\isacharunderscore}def\ mult{\isacharunderscore}prod{\isacharunderscore}def\ \isacommand{by}\isamarkupfalse%
+\ {\isacharparenleft}simp\ add{\isacharcolon}\ neutl{\isacharparenright}\isanewline
+\isacommand{qed}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent Fully-fledged monoids are modelled by another subclass
+  which does not add new parameters but tightens the specification:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{class}\isamarkupfalse%
+\ monoid\ {\isacharequal}\ monoidl\ {\isacharplus}\isanewline
+\ \ \isakeyword{assumes}\ neutr{\isacharcolon}\ {\isachardoublequoteopen}x\ {\isasymotimes}\ {\isasymone}\ {\isacharequal}\ x{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instantiation}\isamarkupfalse%
+\ nat\ \isakeyword{and}\ int\ {\isacharcolon}{\isacharcolon}\ monoid\ \isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ n\ {\isacharcolon}{\isacharcolon}\ nat\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}n\ {\isasymotimes}\ {\isasymone}\ {\isacharequal}\ n{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ neutral{\isacharunderscore}nat{\isacharunderscore}def\ \isacommand{by}\isamarkupfalse%
+\ {\isacharparenleft}induct\ n{\isacharparenright}\ simp{\isacharunderscore}all\isanewline
+\isacommand{next}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ k\ {\isacharcolon}{\isacharcolon}\ int\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}k\ {\isasymotimes}\ {\isasymone}\ {\isacharequal}\ k{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ neutral{\isacharunderscore}int{\isacharunderscore}def\ mult{\isacharunderscore}int{\isacharunderscore}def\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\isacommand{qed}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{instantiation}\isamarkupfalse%
+\ {\isacharasterisk}\ {\isacharcolon}{\isacharcolon}\ {\isacharparenleft}monoid{\isacharcomma}\ monoid{\isacharparenright}\ monoid\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\ \isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ p\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}{\isasymColon}monoid\ {\isasymtimes}\ {\isasymbeta}{\isasymColon}monoid{\isachardoublequoteclose}\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}p\ {\isasymotimes}\ {\isasymone}\ {\isacharequal}\ p{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ neutral{\isacharunderscore}prod{\isacharunderscore}def\ mult{\isacharunderscore}prod{\isacharunderscore}def\ \isacommand{by}\isamarkupfalse%
+\ {\isacharparenleft}simp\ add{\isacharcolon}\ neutr{\isacharparenright}\isanewline
+\isacommand{qed}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent To finish our small algebra example, we add a \isa{group} class
+  with a corresponding instance:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{class}\isamarkupfalse%
+\ group\ {\isacharequal}\ monoidl\ {\isacharplus}\isanewline
+\ \ \isakeyword{fixes}\ inverse\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}\ \ \ \ {\isacharparenleft}{\isachardoublequoteopen}{\isacharparenleft}{\isacharunderscore}{\isasymdiv}{\isacharparenright}{\isachardoublequoteclose}\ {\isacharbrackleft}{\isadigit{1}}{\isadigit{0}}{\isadigit{0}}{\isadigit{0}}{\isacharbrackright}\ {\isadigit{9}}{\isadigit{9}}{\isadigit{9}}{\isacharparenright}\isanewline
+\ \ \isakeyword{assumes}\ invl{\isacharcolon}\ {\isachardoublequoteopen}x{\isasymdiv}\ {\isasymotimes}\ x\ {\isacharequal}\ {\isasymone}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instantiation}\isamarkupfalse%
+\ int\ {\isacharcolon}{\isacharcolon}\ group\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{definition}\isamarkupfalse%
+\isanewline
+\ \ inverse{\isacharunderscore}int{\isacharunderscore}def{\isacharcolon}\ {\isachardoublequoteopen}i{\isasymdiv}\ {\isacharequal}\ {\isacharminus}\ {\isacharparenleft}i{\isasymColon}int{\isacharparenright}{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{instance}\isamarkupfalse%
+\ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ i\ {\isacharcolon}{\isacharcolon}\ int\isanewline
+\ \ \isacommand{have}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isacharminus}i\ {\isacharplus}\ i\ {\isacharequal}\ {\isadigit{0}}{\isachardoublequoteclose}\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\ \ \isacommand{then}\isamarkupfalse%
+\ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}i{\isasymdiv}\ {\isasymotimes}\ i\ {\isacharequal}\ {\isasymone}{\isachardoublequoteclose}\isanewline
+\ \ \ \ \isacommand{unfolding}\isamarkupfalse%
+\ mult{\isacharunderscore}int{\isacharunderscore}def\ neutral{\isacharunderscore}int{\isacharunderscore}def\ inverse{\isacharunderscore}int{\isacharunderscore}def\ \isacommand{{\isachardot}}\isamarkupfalse%
+\isanewline
+\isacommand{qed}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isamarkupsection{Type classes as locales%
+}
+\isamarkuptrue%
+%
+\isamarkupsubsection{A look behind the scene%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+The example above gives an impression how Isar type classes work
+  in practice.  As stated in the introduction, classes also provide
+  a link to Isar's locale system.  Indeed, the logical core of a class
+  is nothing else than a locale:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{class}\isamarkupfalse%
+\ idem\ {\isacharequal}\isanewline
+\ \ \isakeyword{fixes}\ f\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}\isanewline
+\ \ \isakeyword{assumes}\ idem{\isacharcolon}\ {\isachardoublequoteopen}f\ {\isacharparenleft}f\ x{\isacharparenright}\ {\isacharequal}\ f\ x{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent essentially introduces the locale%
+\end{isamarkuptext}%
+\isamarkuptrue%
+\ %
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\isataginvisible
+%
+\endisataginvisible
+{\isafoldinvisible}%
+%
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{locale}\isamarkupfalse%
+\ idem\ {\isacharequal}\isanewline
+\ \ \isakeyword{fixes}\ f\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}\isanewline
+\ \ \isakeyword{assumes}\ idem{\isacharcolon}\ {\isachardoublequoteopen}f\ {\isacharparenleft}f\ x{\isacharparenright}\ {\isacharequal}\ f\ x{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent together with corresponding constant(s):%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{consts}\isamarkupfalse%
+\ f\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}{\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent The connection to the type system is done by means
+  of a primitive axclass%
+\end{isamarkuptext}%
+\isamarkuptrue%
+\ %
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\isataginvisible
+%
+\endisataginvisible
+{\isafoldinvisible}%
+%
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{axclass}\isamarkupfalse%
+\ idem\ {\isacharless}\ type\isanewline
+\ \ idem{\isacharcolon}\ {\isachardoublequoteopen}f\ {\isacharparenleft}f\ x{\isacharparenright}\ {\isacharequal}\ f\ x{\isachardoublequoteclose}\ %
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\isataginvisible
+%
+\endisataginvisible
+{\isafoldinvisible}%
+%
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\begin{isamarkuptext}%
+\noindent together with a corresponding interpretation:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{interpretation}\isamarkupfalse%
+\ idem{\isacharunderscore}class{\isacharcolon}\isanewline
+\ \ idem\ {\isachardoublequoteopen}f\ {\isasymColon}\ {\isacharparenleft}{\isasymalpha}{\isasymColon}idem{\isacharparenright}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}\isanewline
+\isacommand{proof}\isamarkupfalse%
+\ \isacommand{qed}\isamarkupfalse%
+\ {\isacharparenleft}rule\ idem{\isacharparenright}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent This gives you at hand the full power of the Isabelle module system;
+  conclusions in locale \isa{idem} are implicitly propagated
+  to class \isa{idem}.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+\ %
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\isataginvisible
+%
+\endisataginvisible
+{\isafoldinvisible}%
+%
+\isadeliminvisible
+%
+\endisadeliminvisible
+%
+\isamarkupsubsection{Abstract reasoning%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+Isabelle locales enable reasoning at a general level, while results
+  are implicitly transferred to all instances.  For example, we can
+  now establish the \isa{left{\isacharunderscore}cancel} lemma for groups, which
+  states that the function \isa{{\isacharparenleft}x\ {\isasymotimes}{\isacharparenright}} is injective:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{lemma}\isamarkupfalse%
+\ {\isacharparenleft}\isakeyword{in}\ group{\isacharparenright}\ left{\isacharunderscore}cancel{\isacharcolon}\ {\isachardoublequoteopen}x\ {\isasymotimes}\ y\ {\isacharequal}\ x\ {\isasymotimes}\ z\ {\isasymlongleftrightarrow}\ y\ {\isacharequal}\ z{\isachardoublequoteclose}\isanewline
+\isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{assume}\isamarkupfalse%
+\ {\isachardoublequoteopen}x\ {\isasymotimes}\ y\ {\isacharequal}\ x\ {\isasymotimes}\ z{\isachardoublequoteclose}\isanewline
+\ \ \isacommand{then}\isamarkupfalse%
+\ \isacommand{have}\isamarkupfalse%
+\ {\isachardoublequoteopen}x{\isasymdiv}\ {\isasymotimes}\ {\isacharparenleft}x\ {\isasymotimes}\ y{\isacharparenright}\ {\isacharequal}\ x{\isasymdiv}\ {\isasymotimes}\ {\isacharparenleft}x\ {\isasymotimes}\ z{\isacharparenright}{\isachardoublequoteclose}\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\ \ \isacommand{then}\isamarkupfalse%
+\ \isacommand{have}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isacharparenleft}x{\isasymdiv}\ {\isasymotimes}\ x{\isacharparenright}\ {\isasymotimes}\ y\ {\isacharequal}\ {\isacharparenleft}x{\isasymdiv}\ {\isasymotimes}\ x{\isacharparenright}\ {\isasymotimes}\ z{\isachardoublequoteclose}\ \isacommand{using}\isamarkupfalse%
+\ assoc\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\ \ \isacommand{then}\isamarkupfalse%
+\ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}y\ {\isacharequal}\ z{\isachardoublequoteclose}\ \isacommand{using}\isamarkupfalse%
+\ neutl\ \isakeyword{and}\ invl\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\isacommand{next}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{assume}\isamarkupfalse%
+\ {\isachardoublequoteopen}y\ {\isacharequal}\ z{\isachardoublequoteclose}\isanewline
+\ \ \isacommand{then}\isamarkupfalse%
+\ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}x\ {\isasymotimes}\ y\ {\isacharequal}\ x\ {\isasymotimes}\ z{\isachardoublequoteclose}\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\isacommand{qed}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent Here the \qt{\hyperlink{keyword.in}{\mbox{\isa{\isakeyword{in}}}} \isa{group}} target specification
+  indicates that the result is recorded within that context for later
+  use.  This local theorem is also lifted to the global one \hyperlink{fact.group.left-cancel:}{\mbox{\isa{group{\isachardot}left{\isacharunderscore}cancel{\isacharcolon}}}} \isa{{\isachardoublequote}{\isasymAnd}x\ y\ z\ {\isasymColon}\ {\isasymalpha}{\isasymColon}group{\isachardot}\ x\ {\isasymotimes}\ y\ {\isacharequal}\ x\ {\isasymotimes}\ z\ {\isasymlongleftrightarrow}\ y\ {\isacharequal}\ z{\isachardoublequote}}.  Since type \isa{int} has been made an instance of
+  \isa{group} before, we may refer to that fact as well: \isa{{\isachardoublequote}{\isasymAnd}x\ y\ z\ {\isasymColon}\ int{\isachardot}\ x\ {\isasymotimes}\ y\ {\isacharequal}\ x\ {\isasymotimes}\ z\ {\isasymlongleftrightarrow}\ y\ {\isacharequal}\ z{\isachardoublequote}}.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsubsection{Derived definitions%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+Isabelle locales support a concept of local definitions
+  in locales:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{primrec}\isamarkupfalse%
+\ {\isacharparenleft}\isakeyword{in}\ monoid{\isacharparenright}\ pow{\isacharunderscore}nat\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}nat\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}\ \isakeyword{where}\isanewline
+\ \ {\isachardoublequoteopen}pow{\isacharunderscore}nat\ {\isadigit{0}}\ x\ {\isacharequal}\ {\isasymone}{\isachardoublequoteclose}\isanewline
+\ \ {\isacharbar}\ {\isachardoublequoteopen}pow{\isacharunderscore}nat\ {\isacharparenleft}Suc\ n{\isacharparenright}\ x\ {\isacharequal}\ x\ {\isasymotimes}\ pow{\isacharunderscore}nat\ n\ x{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent If the locale \isa{group} is also a class, this local
+  definition is propagated onto a global definition of
+  \isa{{\isachardoublequote}pow{\isacharunderscore}nat\ {\isasymColon}\ nat\ {\isasymRightarrow}\ {\isasymalpha}{\isasymColon}monoid\ {\isasymRightarrow}\ {\isasymalpha}{\isasymColon}monoid{\isachardoublequote}}
+  with corresponding theorems
+
+  \isa{pow{\isacharunderscore}nat\ {\isadigit{0}}\ x\ {\isacharequal}\ {\isasymone}\isasep\isanewline%
+pow{\isacharunderscore}nat\ {\isacharparenleft}Suc\ n{\isacharparenright}\ x\ {\isacharequal}\ x\ {\isasymotimes}\ pow{\isacharunderscore}nat\ n\ x}.
+
+  \noindent As you can see from this example, for local
+  definitions you may use any specification tool
+  which works together with locales (e.g. \cite{krauss2006}).%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsubsection{A functor analogy%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+We introduced Isar classes by analogy to type classes
+  functional programming;  if we reconsider this in the
+  context of what has been said about type classes and locales,
+  we can drive this analogy further by stating that type
+  classes essentially correspond to functors which have
+  a canonical interpretation as type classes.
+  Anyway, there is also the possibility of other interpretations.
+  For example, also \isa{list}s form a monoid with
+  \isa{append} and \isa{{\isacharbrackleft}{\isacharbrackright}} as operations, but it
+  seems inappropriate to apply to lists
+  the same operations as for genuinely algebraic types.
+  In such a case, we simply can do a particular interpretation
+  of monoids for lists:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{interpretation}\isamarkupfalse%
+\ list{\isacharunderscore}monoid{\isacharbang}{\isacharcolon}\ monoid\ append\ {\isachardoublequoteopen}{\isacharbrackleft}{\isacharbrackright}{\isachardoublequoteclose}\isanewline
+\ \ \isacommand{proof}\isamarkupfalse%
+\ \isacommand{qed}\isamarkupfalse%
+\ auto%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent This enables us to apply facts on monoids
+  to lists, e.g. \isa{{\isacharbrackleft}{\isacharbrackright}\ {\isacharat}\ x\ {\isacharequal}\ x}.
+
+  When using this interpretation pattern, it may also
+  be appropriate to map derived definitions accordingly:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{primrec}\isamarkupfalse%
+\ replicate\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}nat\ {\isasymRightarrow}\ {\isasymalpha}\ list\ {\isasymRightarrow}\ {\isasymalpha}\ list{\isachardoublequoteclose}\ \isakeyword{where}\isanewline
+\ \ {\isachardoublequoteopen}replicate\ {\isadigit{0}}\ {\isacharunderscore}\ {\isacharequal}\ {\isacharbrackleft}{\isacharbrackright}{\isachardoublequoteclose}\isanewline
+\ \ {\isacharbar}\ {\isachardoublequoteopen}replicate\ {\isacharparenleft}Suc\ n{\isacharparenright}\ xs\ {\isacharequal}\ xs\ {\isacharat}\ replicate\ n\ xs{\isachardoublequoteclose}\isanewline
+\isanewline
+\isacommand{interpretation}\isamarkupfalse%
+\ list{\isacharunderscore}monoid{\isacharbang}{\isacharcolon}\ monoid\ append\ {\isachardoublequoteopen}{\isacharbrackleft}{\isacharbrackright}{\isachardoublequoteclose}\ \isakeyword{where}\isanewline
+\ \ {\isachardoublequoteopen}monoid{\isachardot}pow{\isacharunderscore}nat\ append\ {\isacharbrackleft}{\isacharbrackright}\ {\isacharequal}\ replicate{\isachardoublequoteclose}\isanewline
+\isacommand{proof}\isamarkupfalse%
+\ {\isacharminus}\isanewline
+\ \ \isacommand{interpret}\isamarkupfalse%
+\ monoid\ append\ {\isachardoublequoteopen}{\isacharbrackleft}{\isacharbrackright}{\isachardoublequoteclose}\ \isacommand{{\isachardot}{\isachardot}}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}monoid{\isachardot}pow{\isacharunderscore}nat\ append\ {\isacharbrackleft}{\isacharbrackright}\ {\isacharequal}\ replicate{\isachardoublequoteclose}\isanewline
+\ \ \isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \ \ \isacommand{fix}\isamarkupfalse%
+\ n\isanewline
+\ \ \ \ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}monoid{\isachardot}pow{\isacharunderscore}nat\ append\ {\isacharbrackleft}{\isacharbrackright}\ n\ {\isacharequal}\ replicate\ n{\isachardoublequoteclose}\isanewline
+\ \ \ \ \ \ \isacommand{by}\isamarkupfalse%
+\ {\isacharparenleft}induct\ n{\isacharparenright}\ auto\isanewline
+\ \ \isacommand{qed}\isamarkupfalse%
+\isanewline
+\isacommand{qed}\isamarkupfalse%
+\ intro{\isacharunderscore}locales%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isamarkupsubsection{Additional subclass relations%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+Any \isa{group} is also a \isa{monoid};  this
+  can be made explicit by claiming an additional
+  subclass relation,
+  together with a proof of the logical difference:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{subclass}\isamarkupfalse%
+\ {\isacharparenleft}\isakeyword{in}\ group{\isacharparenright}\ monoid\isanewline
+\isacommand{proof}\isamarkupfalse%
+\isanewline
+\ \ \isacommand{fix}\isamarkupfalse%
+\ x\isanewline
+\ \ \isacommand{from}\isamarkupfalse%
+\ invl\ \isacommand{have}\isamarkupfalse%
+\ {\isachardoublequoteopen}x{\isasymdiv}\ {\isasymotimes}\ x\ {\isacharequal}\ {\isasymone}{\isachardoublequoteclose}\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\ \ \isacommand{with}\isamarkupfalse%
+\ assoc\ {\isacharbrackleft}symmetric{\isacharbrackright}\ neutl\ invl\ \isacommand{have}\isamarkupfalse%
+\ {\isachardoublequoteopen}x{\isasymdiv}\ {\isasymotimes}\ {\isacharparenleft}x\ {\isasymotimes}\ {\isasymone}{\isacharparenright}\ {\isacharequal}\ x{\isasymdiv}\ {\isasymotimes}\ x{\isachardoublequoteclose}\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\ \ \isacommand{with}\isamarkupfalse%
+\ left{\isacharunderscore}cancel\ \isacommand{show}\isamarkupfalse%
+\ {\isachardoublequoteopen}x\ {\isasymotimes}\ {\isasymone}\ {\isacharequal}\ x{\isachardoublequoteclose}\ \isacommand{by}\isamarkupfalse%
+\ simp\isanewline
+\isacommand{qed}\isamarkupfalse%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+The logical proof is carried out on the locale level.
+  Afterwards it is propagated
+  to the type system, making \isa{group} an instance of
+  \isa{monoid} by adding an additional edge
+  to the graph of subclass relations
+  (cf.\ \figref{fig:subclass}).
+
+  \begin{figure}[htbp]
+   \begin{center}
+     \small
+     \unitlength 0.6mm
+     \begin{picture}(40,60)(0,0)
+       \put(20,60){\makebox(0,0){\isa{semigroup}}}
+       \put(20,40){\makebox(0,0){\isa{monoidl}}}
+       \put(00,20){\makebox(0,0){\isa{monoid}}}
+       \put(40,00){\makebox(0,0){\isa{group}}}
+       \put(20,55){\vector(0,-1){10}}
+       \put(15,35){\vector(-1,-1){10}}
+       \put(25,35){\vector(1,-3){10}}
+     \end{picture}
+     \hspace{8em}
+     \begin{picture}(40,60)(0,0)
+       \put(20,60){\makebox(0,0){\isa{semigroup}}}
+       \put(20,40){\makebox(0,0){\isa{monoidl}}}
+       \put(00,20){\makebox(0,0){\isa{monoid}}}
+       \put(40,00){\makebox(0,0){\isa{group}}}
+       \put(20,55){\vector(0,-1){10}}
+       \put(15,35){\vector(-1,-1){10}}
+       \put(05,15){\vector(3,-1){30}}
+     \end{picture}
+     \caption{Subclass relationship of monoids and groups:
+        before and after establishing the relationship
+        \isa{group\ {\isasymsubseteq}\ monoid};  transitive edges are left out.}
+     \label{fig:subclass}
+   \end{center}
+  \end{figure}
+
+  For illustration, a derived definition
+  in \isa{group} which uses \isa{pow{\isacharunderscore}nat}:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{definition}\isamarkupfalse%
+\ {\isacharparenleft}\isakeyword{in}\ group{\isacharparenright}\ pow{\isacharunderscore}int\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequoteopen}int\ {\isasymRightarrow}\ {\isasymalpha}\ {\isasymRightarrow}\ {\isasymalpha}{\isachardoublequoteclose}\ \isakeyword{where}\isanewline
+\ \ {\isachardoublequoteopen}pow{\isacharunderscore}int\ k\ x\ {\isacharequal}\ {\isacharparenleft}if\ k\ {\isachargreater}{\isacharequal}\ {\isadigit{0}}\isanewline
+\ \ \ \ then\ pow{\isacharunderscore}nat\ {\isacharparenleft}nat\ k{\isacharparenright}\ x\isanewline
+\ \ \ \ else\ {\isacharparenleft}pow{\isacharunderscore}nat\ {\isacharparenleft}nat\ {\isacharparenleft}{\isacharminus}\ k{\isacharparenright}{\isacharparenright}\ x{\isacharparenright}{\isasymdiv}{\isacharparenright}{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent yields the global definition of
+  \isa{{\isachardoublequote}pow{\isacharunderscore}int\ {\isasymColon}\ int\ {\isasymRightarrow}\ {\isasymalpha}{\isasymColon}group\ {\isasymRightarrow}\ {\isasymalpha}{\isasymColon}group{\isachardoublequote}}
+  with the corresponding theorem \isa{pow{\isacharunderscore}int\ k\ x\ {\isacharequal}\ {\isacharparenleft}if\ {\isadigit{0}}\ {\isasymle}\ k\ then\ pow{\isacharunderscore}nat\ {\isacharparenleft}nat\ k{\isacharparenright}\ x\ else\ {\isacharparenleft}pow{\isacharunderscore}nat\ {\isacharparenleft}nat\ {\isacharparenleft}{\isacharminus}\ k{\isacharparenright}{\isacharparenright}\ x{\isacharparenright}{\isasymdiv}{\isacharparenright}}.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsubsection{A note on syntax%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+As a commodity, class context syntax allows to refer
+  to local class operations and their global counterparts
+  uniformly;  type inference resolves ambiguities.  For example:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{context}\isamarkupfalse%
+\ semigroup\isanewline
+\isakeyword{begin}\isanewline
+\isanewline
+\isacommand{term}\isamarkupfalse%
+\ {\isachardoublequoteopen}x\ {\isasymotimes}\ y{\isachardoublequoteclose}\ %
+\isamarkupcmt{example 1%
+}
+\isanewline
+\isacommand{term}\isamarkupfalse%
+\ {\isachardoublequoteopen}{\isacharparenleft}x{\isasymColon}nat{\isacharparenright}\ {\isasymotimes}\ y{\isachardoublequoteclose}\ %
+\isamarkupcmt{example 2%
+}
+\isanewline
+\isanewline
+\isacommand{end}\isamarkupfalse%
+\isanewline
+\isanewline
+\isacommand{term}\isamarkupfalse%
+\ {\isachardoublequoteopen}x\ {\isasymotimes}\ y{\isachardoublequoteclose}\ %
+\isamarkupcmt{example 3%
+}
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent Here in example 1, the term refers to the local class operation
+  \isa{mult\ {\isacharbrackleft}{\isasymalpha}{\isacharbrackright}}, whereas in example 2 the type constraint
+  enforces the global class operation \isa{mult\ {\isacharbrackleft}nat{\isacharbrackright}}.
+  In the global context in example 3, the reference is
+  to the polymorphic global class operation \isa{mult\ {\isacharbrackleft}{\isacharquery}{\isasymalpha}\ {\isasymColon}\ semigroup{\isacharbrackright}}.%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isamarkupsection{Further issues%
+}
+\isamarkuptrue%
+%
+\isamarkupsubsection{Type classes and code generation%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+Turning back to the first motivation for type classes,
+  namely overloading, it is obvious that overloading
+  stemming from \hyperlink{command.class}{\mbox{\isa{\isacommand{class}}}} statements and
+  \hyperlink{command.instantiation}{\mbox{\isa{\isacommand{instantiation}}}}
+  targets naturally maps to Haskell type classes.
+  The code generator framework \cite{isabelle-codegen} 
+  takes this into account.  Concerning target languages
+  lacking type classes (e.g.~SML), type classes
+  are implemented by explicit dictionary construction.
+  As example, let's go back to the power function:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+\isacommand{definition}\isamarkupfalse%
+\ example\ {\isacharcolon}{\isacharcolon}\ int\ \isakeyword{where}\isanewline
+\ \ {\isachardoublequoteopen}example\ {\isacharequal}\ pow{\isacharunderscore}int\ {\isadigit{1}}{\isadigit{0}}\ {\isacharparenleft}{\isacharminus}{\isadigit{2}}{\isacharparenright}{\isachardoublequoteclose}%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent This maps to Haskell as:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+%
+\begin{isamarkuptext}%
+\isatypewriter%
+\noindent%
+\hspace*{0pt}module Example where {\char123}\\
+\hspace*{0pt}\\
+\hspace*{0pt}\\
+\hspace*{0pt}data Nat = Zero{\char95}nat | Suc Nat;\\
+\hspace*{0pt}\\
+\hspace*{0pt}nat{\char95}aux ::~Integer -> Nat -> Nat;\\
+\hspace*{0pt}nat{\char95}aux i n = (if i <= 0 then n else nat{\char95}aux (i - 1) (Suc n));\\
+\hspace*{0pt}\\
+\hspace*{0pt}nat ::~Integer -> Nat;\\
+\hspace*{0pt}nat i = nat{\char95}aux i Zero{\char95}nat;\\
+\hspace*{0pt}\\
+\hspace*{0pt}class Semigroup a where {\char123}\\
+\hspace*{0pt} ~mult ::~a -> a -> a;\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}class (Semigroup a) => Monoidl a where {\char123}\\
+\hspace*{0pt} ~neutral ::~a;\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}class (Monoidl a) => Monoid a where {\char123}\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}class (Monoid a) => Group a where {\char123}\\
+\hspace*{0pt} ~inverse ::~a -> a;\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}inverse{\char95}int ::~Integer -> Integer;\\
+\hspace*{0pt}inverse{\char95}int i = negate i;\\
+\hspace*{0pt}\\
+\hspace*{0pt}neutral{\char95}int ::~Integer;\\
+\hspace*{0pt}neutral{\char95}int = 0;\\
+\hspace*{0pt}\\
+\hspace*{0pt}mult{\char95}int ::~Integer -> Integer -> Integer;\\
+\hspace*{0pt}mult{\char95}int i j = i + j;\\
+\hspace*{0pt}\\
+\hspace*{0pt}instance Semigroup Integer where {\char123}\\
+\hspace*{0pt} ~mult = mult{\char95}int;\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}instance Monoidl Integer where {\char123}\\
+\hspace*{0pt} ~neutral = neutral{\char95}int;\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}instance Monoid Integer where {\char123}\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}instance Group Integer where {\char123}\\
+\hspace*{0pt} ~inverse = inverse{\char95}int;\\
+\hspace*{0pt}{\char125};\\
+\hspace*{0pt}\\
+\hspace*{0pt}pow{\char95}nat ::~forall a.~(Monoid a) => Nat -> a -> a;\\
+\hspace*{0pt}pow{\char95}nat Zero{\char95}nat x = neutral;\\
+\hspace*{0pt}pow{\char95}nat (Suc n) x = mult x (pow{\char95}nat n x);\\
+\hspace*{0pt}\\
+\hspace*{0pt}pow{\char95}int ::~forall a.~(Group a) => Integer -> a -> a;\\
+\hspace*{0pt}pow{\char95}int k x =\\
+\hspace*{0pt} ~(if 0 <= k then pow{\char95}nat (nat k) x\\
+\hspace*{0pt} ~~~else inverse (pow{\char95}nat (nat (negate k)) x));\\
+\hspace*{0pt}\\
+\hspace*{0pt}example ::~Integer;\\
+\hspace*{0pt}example = pow{\char95}int 10 (-2);\\
+\hspace*{0pt}\\
+\hspace*{0pt}{\char125}%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\begin{isamarkuptext}%
+\noindent The whole code in SML with explicit dictionary passing:%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isatagquote
+%
+\begin{isamarkuptext}%
+\isatypewriter%
+\noindent%
+\hspace*{0pt}structure Example = \\
+\hspace*{0pt}struct\\
+\hspace*{0pt}\\
+\hspace*{0pt}datatype nat = Zero{\char95}nat | Suc of nat;\\
+\hspace*{0pt}\\
+\hspace*{0pt}fun nat{\char95}aux i n =\\
+\hspace*{0pt} ~(if IntInf.<= (i,~(0 :~IntInf.int)) then n\\
+\hspace*{0pt} ~~~else nat{\char95}aux (IntInf.- (i,~(1 :~IntInf.int))) (Suc n));\\
+\hspace*{0pt}\\
+\hspace*{0pt}fun nat i = nat{\char95}aux i Zero{\char95}nat;\\
+\hspace*{0pt}\\
+\hspace*{0pt}type 'a semigroup = {\char123}mult :~'a -> 'a -> 'a{\char125};\\
+\hspace*{0pt}fun mult (A{\char95}:'a semigroup) = {\char35}mult A{\char95};\\
+\hspace*{0pt}\\
+\hspace*{0pt}type 'a monoidl =\\
+\hspace*{0pt} ~{\char123}Classes{\char95}{\char95}semigroup{\char95}monoidl :~'a semigroup,~neutral :~'a{\char125};\\
+\hspace*{0pt}fun semigroup{\char95}monoidl (A{\char95}:'a monoidl) = {\char35}Classes{\char95}{\char95}semigroup{\char95}monoidl A{\char95};\\
+\hspace*{0pt}fun neutral (A{\char95}:'a monoidl) = {\char35}neutral A{\char95};\\
+\hspace*{0pt}\\
+\hspace*{0pt}type 'a monoid = {\char123}Classes{\char95}{\char95}monoidl{\char95}monoid :~'a monoidl{\char125};\\
+\hspace*{0pt}fun monoidl{\char95}monoid (A{\char95}:'a monoid) = {\char35}Classes{\char95}{\char95}monoidl{\char95}monoid A{\char95};\\
+\hspace*{0pt}\\
+\hspace*{0pt}type 'a group = {\char123}Classes{\char95}{\char95}monoid{\char95}group :~'a monoid,~inverse :~'a -> 'a{\char125};\\
+\hspace*{0pt}fun monoid{\char95}group (A{\char95}:'a group) = {\char35}Classes{\char95}{\char95}monoid{\char95}group A{\char95};\\
+\hspace*{0pt}fun inverse (A{\char95}:'a group) = {\char35}inverse A{\char95};\\
+\hspace*{0pt}\\
+\hspace*{0pt}fun inverse{\char95}int i = IntInf.{\char126}~i;\\
+\hspace*{0pt}\\
+\hspace*{0pt}val neutral{\char95}int :~IntInf.int = (0 :~IntInf.int)\\
+\hspace*{0pt}\\
+\hspace*{0pt}fun mult{\char95}int i j = IntInf.+ (i,~j);\\
+\hspace*{0pt}\\
+\hspace*{0pt}val semigroup{\char95}int = {\char123}mult = mult{\char95}int{\char125}~:~IntInf.int semigroup;\\
+\hspace*{0pt}\\
+\hspace*{0pt}val monoidl{\char95}int =\\
+\hspace*{0pt} ~{\char123}Classes{\char95}{\char95}semigroup{\char95}monoidl = semigroup{\char95}int,~neutral = neutral{\char95}int{\char125}~:\\
+\hspace*{0pt} ~IntInf.int monoidl;\\
+\hspace*{0pt}\\
+\hspace*{0pt}val monoid{\char95}int = {\char123}Classes{\char95}{\char95}monoidl{\char95}monoid = monoidl{\char95}int{\char125}~:\\
+\hspace*{0pt} ~IntInf.int monoid;\\
+\hspace*{0pt}\\
+\hspace*{0pt}val group{\char95}int =\\
+\hspace*{0pt} ~{\char123}Classes{\char95}{\char95}monoid{\char95}group = monoid{\char95}int,~inverse = inverse{\char95}int{\char125}~:\\
+\hspace*{0pt} ~IntInf.int group;\\
+\hspace*{0pt}\\
+\hspace*{0pt}fun pow{\char95}nat A{\char95}~Zero{\char95}nat x = neutral (monoidl{\char95}monoid A{\char95})\\
+\hspace*{0pt} ~| pow{\char95}nat A{\char95}~(Suc n) x =\\
+\hspace*{0pt} ~~~mult ((semigroup{\char95}monoidl o monoidl{\char95}monoid) A{\char95}) x (pow{\char95}nat A{\char95}~n x);\\
+\hspace*{0pt}\\
+\hspace*{0pt}fun pow{\char95}int A{\char95}~k x =\\
+\hspace*{0pt} ~(if IntInf.<= ((0 :~IntInf.int),~k)\\
+\hspace*{0pt} ~~~then pow{\char95}nat (monoid{\char95}group A{\char95}) (nat k) x\\
+\hspace*{0pt} ~~~else inverse A{\char95}~(pow{\char95}nat (monoid{\char95}group A{\char95}) (nat (IntInf.{\char126}~k)) x));\\
+\hspace*{0pt}\\
+\hspace*{0pt}val example :~IntInf.int =\\
+\hspace*{0pt} ~pow{\char95}int group{\char95}int (10 :~IntInf.int) ({\char126}2 :~IntInf.int)\\
+\hspace*{0pt}\\
+\hspace*{0pt}end;~(*struct Example*)%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\endisatagquote
+{\isafoldquote}%
+%
+\isadelimquote
+%
+\endisadelimquote
+%
+\isamarkupsubsection{Inspecting the type class universe%
+}
+\isamarkuptrue%
+%
+\begin{isamarkuptext}%
+To facilitate orientation in complex subclass structures,
+  two diagnostics commands are provided:
+
+  \begin{description}
+
+    \item[\hyperlink{command.print-classes}{\mbox{\isa{\isacommand{print{\isacharunderscore}classes}}}}] print a list of all classes
+      together with associated operations etc.
+
+    \item[\hyperlink{command.class-deps}{\mbox{\isa{\isacommand{class{\isacharunderscore}deps}}}}] visualizes the subclass relation
+      between all classes as a Hasse diagram.
+
+  \end{description}%
+\end{isamarkuptext}%
+\isamarkuptrue%
+%
+\isadelimtheory
+%
+\endisadelimtheory
+%
+\isatagtheory
+\isacommand{end}\isamarkupfalse%
+%
+\endisatagtheory
+{\isafoldtheory}%
+%
+\isadelimtheory
+%
+\endisadelimtheory
+\isanewline
+\end{isabellebody}%
+%%% Local Variables:
+%%% mode: latex
+%%% TeX-master: "root"
+%%% End:




