Standard ML is a general-purpose, modular, functional programming language. 

 Standard ML is a general-purpose, modular, functional programming language. \cite{pl:milner97}

 SML is a modern descendant of the ML programming language used in the Logic for Computable Functions (LCF) theorem-proving project. 

 Functional programming languages constitude a ???? very differnt of object orientated languages, see Sect. \ref{ml-users}. ML originated from the LCF-project(Logic for Computable Functions)\cite{meta-Ml}, where it had been developed as a meta language. Since ML has been standardised this family of language is called Standard ML. Important for the logical foundation of SML is the $\lambda$-calculus.

 It is invented by Robin Milner. %http://en.wikipedia.org/wiki/Standard_M 

 %http://en.wikipedia.org/wiki/Standard_M 

 Coq is an interactive theorem prover, developed in France. The team leader is Senior Scientist Benjamin Werner. 

 Coq is an interactive theorem prover, developed in France.

 Coq is in Objective Caml programmed, an ML based programming language.

 It is programmed in Objective Caml, an ML based programming language.

 It has the ability to express  mathematical  assertions and check proof of mathematical  assertions. 

 It has the ability to express  mathematical  assertions and check proof of mathematical assertions. 

 Proof development in Coq is done through a language of tactics that allows a user-guided proof process. 

 Properties, programs and proofs are written a functional programming language called the Calculus of Inductive Constructions (CIC).

 At the end, the user can check that tactics build lambda-terms. 

 Proof development in Coq is done through a language of tactics that allows a user-guided proof process.\cite{coq1999}

 Properties, programs and proofs are written a language called the Calculus of Inductive Constructions (CIC).

 Coq is based on a type-checking algorithm, therefore Coq uses only typing judgements.

 There are many easy-to-read introductions to Coq \footnote{http://coq.inria.fr/a-short-introduction-to-coq} on the internet.

 Coq supports a functional programming language.

 (http://coq.inria.fr/a-short-introduction-to-coq)

 Isabelle is developed at University of Cambridge (Larry Paulson), Technische Universität München (Tobias Nipkow) 

 Isabelle is developed at University of Cambridge (Larry Paulson), Technische Universit\"at M\"unchen

 and Université Paris-Sud (Makarius Wenzel).

 and Université Paris-Sud. Isabelle is called a framework, because it implements serveral object logics.

 The most widespread instance of Isabelle nowadays is Isabelle/HOL, providing a higher-order logic theorem proving environment.

 The most widespread logic of Isabelle is Isabelle/HOL, short for higher-order logic.

 Proofs are written in the structured proof language Isar. Isabelle implements several tools to increase the user's productivity in theorem proving. 

 Proofs are written in the structured proof language Isar.\cite{wenzel:isar} Isabelle implements several tools, e.g. a reasoner, a simplifier and powerful automatic provers(Slegehammer), increase the user's productivity in theorem proving. 

 Isabelle's classical reasoner is used to check formulas. The simplifier can reason with and about equations. 

 Linear arithmetic facts are proved automatically.

 Isabelle/HOL allows to turn executable specifications directly into code in SML, OCaml, and Haskell.

 Isabelle/HOL allows to turn executable specifications directly into code in SML, OCaml, and Haskell.\cite{Haftmann-Nipkow:2010:code}

 Proof General has been developed at the LFCS in the University of Edinburgh with contributions from other sites.

 It has been developed at  the University of Edinburgh with contributions from other sites.

 The main Isabelle/jEdit plugin consists of ≈ 10 small Scala files  that augment some key jEdit components in order to provide a metaphor of asynchronous 

 The main Isabelle/jEdit plugin consists of ten small Scala files  that augment some key jEdit components in order to provide a metaphor of asynchronous 

 This achieves continuous proof checking based on our 

 This achieves continuous proof checking based on 

 The importance of connecting the ML-world with the world of user interfaces has been is discussed in Sect.\ref{ml-users}. jEdit follows these lines, it is an open-source, Java-based text editor that works on Windows, Mac OS X, and Linux. A big advantage of jEdit is, that there is a very good and also simple way to use and write a Plugin. There are a lot of useful and powerful Plugins available in the net and it is also possible to use a existing Plugin as part of a new one. Because of this facts, jEdit is very suitable for a project like Isabelle and also for the \sisac-project at TU-Graz.

 The importance of connecting the ML-world with the world of user interfaces has been is discussed in Sect.\ref{ml-users}. jEdit follows these lines, it is an open-source, Java-based text editor that works on Windows, Mac OS X, and Linux. A big advantage of jEdit is, that there is a very good and also simple way to use and write a Plugin. There are a lot of useful and powerful Plugins available in the net and it is also possible to use a existing Plugin as part of a new one. Because of this facts, jEdit is very suitable for a project like Isabelle and also for the Isac-project at TU-Graz. \\\\

 Each jEdit-Plugin basically consists of source files, written in Java or Scala, XML-files and property files. The XML-Files are important for the administration of a Plugin and provides information like the name, author, ... of the Plugin. They are also containing small pieces of BeanShell code which is executed upon a user request. (Like pressing the 'start plugin' button.) So the XML-files provide the “glue” between user input and specific Plugin routines located in the source files. As you see, this files are used as interface between the Plugin and the jEdit engine itself.\\

 Each jEdit-Plugin\footnote{To get more information about the jEdit infrastructure see: http://jedit.org/users-guide/plugin-intro} basically consists of source files, written in Java or Scala, XML-files and property files. The XML-Files are important for the administration of a Plugin and provides information like the name, author, ... of the Plugin. They are also containing small pieces of BeanShell code which is executed upon a user request. (Like pressing the 'start plugin' button.) So the XML-files provide the “glue” between user input and specific Plugin routines located in the source files. As you see, this files are used as interface between the Plugin and the jEdit engine itself.

 To get more information about the jEdit infrastructure see: http://jedit.org/users-guide/plugin-intro

 \\\\

 \begin{description}

 The property-file \textit{Isabelle.props} contains general informations about the Isabelle-Plugin and the needed dependencies between Isabelle and the other used Plugins like sidekick. \\

 \item[Isabelle.props] The property-file \textit{Isabelle.props} contains general informations about the Isabelle-Plugin and the needed dependencies between Isabelle and the other used Plugins like sidekick.

 The XML-file \textit{dockables.xml} is used to create the needed dock-able windows which are important to set up the GUI of the Plugin.\\

 \item[dockables.xml] The XML-file \textit{dockables.xml} is used to create the needed dock-able windows which are important to set up the GUI of the Plugin.

 In the file \textit{actions.xml}, the dockable windows are added to the window-manager \textit{wm} and there is also some Beanshell-code to activate the Isabelle-GUI.\\

 \item[actions.xml] In the file \textit{actions.xml}, the dockable windows are added to the window-manager \textit{wm} and there is also some Beanshell-code to activate the Isabelle-GUI.

 The last XML-file is \textit{services.xml} and is used to create instances of needed jEdit-Plugins.\\

 \item[services.xml] The last XML-file is \textit{services.xml} and is used to create instances of needed jEdit-Plugins.

 This four files are located in the folder \textit{plugin}.\\\\

 \end{description}

 The more interesting files, the scala-files of the Plugin, can be found in the 'src/jedit'-directory. In this directory you can find the file \textit{Dummy.java} which is a dummy class and is simply used to make javadoc work. Just forget about this file. Also there is a folder/package \textit{jedit} which contains all Scala-source-files. Now it is time to take a closer look on the source-files: \\

 This four files are located in the folder \textit{plugin}.\\

 The file \textit{plugin.scala} is the main-file of the Isabelle-Plugin and there are two important parts. First the \textit{Isabelle object}. This object contains data like name and path and also few basic functions. The second part is the \textit{class Plugin} which is derived from EBPlugin. Here the basic methods \textit{handleMessage}, \textit{start} and \textit{stop} are implemented. Each jEdit-Plugin should have this methods because they are very important for the handling of the Plugin! \\

 jEdit and also the Isabelle Plugin work with dock-able windows. This means that you can move around each single window and dock it somewhere on the screen. So it is possible to individualize the jEdit-GUI. To support this, the file \textit{dockable.scala} is needed. The file \textit{output-dockable.scala} is derived from \textit{dockable.scala} and is used to print the result/output in a dock-able window. The same thing with \textit{protocol-dockable.scala} and \textit{raw-output-dockable.scala}.\\

 The more interesting files, the scala-files of the Plugin, can be found in the 'src/jedit'-directory. In this directory you can find the file \textit{Dummy.java} which is a dummy class and is simply used to make javadoc work. Just forget about this file. Also there is a folder/package \textit{jedit} which contains all Scala-source-files. Now it is time to take a closer look on the source-files: 

 The next interesting file is \textit{scala-console.scala} with the main-class Scala-Console. This class is used to expand the Console-Plugin in a way, that it is possible to interpret Scala-code with a Shell inside of jEdit.\\ 

 \begin{description}

 The file \textit{isabelle-sidekick.scala} is related to the file \textit{scala-console.scala} because it is also used to adapt the Plugin Sidekick for Isabelle.\\

 \item[plugin.scala] The file \textit{plugin.scala} is the main-file of the Isabelle-Plugin and there are two important parts. First the \textit{Isabelle object}. This object contains data like name and path and also few basic functions. The second part is the \textit{class Plugin} which is derived from EBPlugin. Here the basic methods \textit{handleMessage}, \textit{start} and \textit{stop} are implemented. Each jEdit-Plugin should have this methods because they are very important for the handling of the Plugin!

 The files \textit{document-model.scala} and \textit{document-view.scala1} are used to connect the jEdit-buffer/the text-area to Isabelle. Both classes offer, upon others, methods to activate and deactivate this features.\\

 \item[dockable.scala] jEdit and also the Isabelle Plugin work with dock-able windows. This means that you can move around each single window and dock it somewhere on the screen. So it is possible to individualize the jEdit-GUI. To support this, the file \textit{dockable.scala} is needed. The file \textit{output-dockable.scala} is derived from \textit{dockable.scala} and is used to print the result/output in a dock-able window. The same thing with \textit{protocol-dockable.scala} and \textit{raw-output-dockable.scala}.

 There also some other source-files but they aren’t discussed here, because the main goal of this paragraph is to give a basic idea how a jEdit-Plugin should be set up and the remaining files are not as important for the Isabelle-Plugin-structure:

 \item[scala-console.scala] The next interesting file is \textit{scala-console.scala} with the main-class Scala-Console. This class is used to expand the Console-Plugin in a way, that it is possible to interpret Scala-code with a Shell inside of jEdit.

 \begin{itemize}

 \item[isabelle-sidekick.scala] The file \textit{isabelle-sidekick.scala} is related to the file \textit{scala-console.scala} because it is also used to adapt the Plugin Sidekick for Isabelle.

 \item $html_panel.scala$

 \item[document-model.scala, document-view.scala] The files \textit{document-model.scala} and \textit{document-view.scala} are used to connect the jEdit-buffer/the text-area to Isabelle. Both classes offer, upon others, methods to activate and deactivate this features.

 \item $isabelle_encoding.scala$

 \end{description}

 \item $isabelle_hyperlinks.scala$

 There also some other source-files but they aren’t discussed here, because the main goal of this paragraph is to give a basic idea how a jEdit-Plugin should be set up and the remaining files are not as important for the Isabelle-Plugin-structure.

 \item $isabelle_options.scala$

 %\begin{itemize}

 \item $isabelle_token_maker.scala$

 %\item $html_panel.scala$

 \item $isabelle_hyperlinks.scala$

 %\item $isabelle_encoding.scala$

 \end{itemize}

 %\item $isabelle_hyperlinks.scala$

 %\item $isabelle_options.scala$

 %\item $isabelle_token_maker.scala$

 %\item $isabelle_hyperlinks.scala$

 %\end{itemize}

 As described in the last paragraph, jEdit is a open-source-project. The jEdit-developers use a NetBeans-project to produce the source-code and so it is beneficial to use a NetBeans project too, because there is a quite good documentation about setting up a NetBeans-project with the jEdit-source.\footnote{See http://wiki.netbeans.org/NetbeansedJEdit for further information.} 

 As described in the last paragraph, jEdit is a open-source-project. The jEdit-developers use a NetBeans-project to produce the source-code and so it is beneficial to use a NetBeans project too, because there is a quite good documentation about setting up a NetBeans-project with the jEdit-source. See http://wiki.netbeans.org/NetbeansedJEdit for further information.\\\\

 %\begin{itemize}

 \begin{itemize}

 %\item with jEdit source code - two projects in one

 \item with jEdit source code - two projects in one

 %\item with jedit.jar library

 \item with jedit.jar library

 %\end{itemize}

 \end{itemize}

 As you see in the paragraph above, it is also important to have basic knowledge about NetBeans, the project structure and how to change the operational sequences. A typical NetBeans-project consist of the source- and library-files and administrative XML- and property-files. In this paragraph the administrative part of the project is of note. The most important file is \textit{build.xml}. This file can be found in the project directory. There is also a folder \textit{nbproject} which contains the remaining XML- and property-files and also a folder \textit{private}, where individual user informations about the project is stored. The files in this \textit{private} folder are not important to describe (and they should not be pushed on the repository!).

 As you see in the paragraph above, it is also important to have basic knowledge about NetBeans, the project structure and how to change the operational sequences. A typical NetBeans-project consist of the source- and library-files and administrative XML- and property-files. In this paragraph the administrative part of the project is of note. The most important file is \textit{build.xml}. This file can be found in the project directory. There is also a folder \textit{nbproject} which contains the remaining XML- and property-files and also a folder \textit{private}, where individual user informations about the project is stored. The files in this \textit{private} folder are not important to describe (and they should not be pushed on the repository!).\\

 A build-file like \textit{build.xml} contains one project and at least one (default) target. Targets contain task elements. Each task element of the build-file can have an id attribute and can later be referred to by the value supplied to this. So the id has to be unique. Such targets can be "run", "debug", "build", ... and can have dependencies to other targets. Tasks define what should happen, if a target is executed. So like in the example above, the target is \textit{pre-jar}, that means that this things will happen before the jar-package is packed. The tasks of this target are copying some files into the package.\\

 A build-file like \textit{build.xml} contains one project and at least one (default) target. Targets contain task elements. Each task element of the build-file can have an id attribute and can later be referred to by the value supplied to this. So the id has to be unique. Such targets can be "run", "debug", "build", ... and can have dependencies to other targets. Tasks define what should happen, if a target is executed. So like in the example above, the target is \textit{pre-jar}, that means that this things will happen before the jar-package is packed. The tasks of this target are copying some files into the package.

 jEdit is completely written in Java and the required plugin(s) for \sisac{ }will be coded in Scala - so there must be ways to exchange data between Java and Scala. One way is to connect this two worlds with the in 4.2 described XML-files. Here you need to use a third type of code to get an interface between Java and Scala code. But there is also a way to get a direct connection.

 jEdit is completely written in Java and the required plugin(s) for Isac will be coded in Scala - so there must be ways to exchange data between Java and Scala. One way is to connect this two worlds with the in 4.2 described XML-files. Here you need to use a third type of code to get an interface between Java and Scala code. But there is also a way to get a direct connection.\\

 This link should be shown on the graphic-library \textit{Swing}. In both languages it is possible to use Swing which provides a lot of different shapes and useful functionality. So there is a Java-Swing and also a Scala-Swing-library. Now it is interesting to examine the connection between this two libraries.\\

 This link should be shown on the graphic-library \textit{Swing}. In both languages it is possible to use Swing which provides a lot of different shapes and useful functionality. So there is a Java-Swing and also a Scala-Swing-library. Now it is interesting to examine the connection between this two libraries.

 In Scala a direct use of Java-Libs (like Java-Swing) is possible. So if you are Java-Programmer and want to use Java-Swing in Scala, you can simply type \textit{import javax.swing.JButton} to work with a Java-button. But you can also use the Scala-equivalent \textit{scala.swing.Button}. This two button-types will provide nearly the same functionality.\\So what is the idea of creating a nearly similar library a second time? Why have the Scala-developers done such extra work? The answer is, that they have tried to improve and simplify the usage of the Swing-library(and many other libs too!). So big parts of this Scala-Libraries are just Wrapper-objects, Wrapper-Classes and Wrapper-Methods of already existing parts in Java-Libraries. Needless to say that they also added new useful shapes and functionality.\\

 In Scala a direct use of Java-Libs (like Java-Swing) is possible. So if you are Java-Programmer and want to use Java-Swing in Scala, you can simply type\\ \textit{import javax.swing.JButton}\footnote{http://download.oracle.com/javase/1.4.2/docs/api/javax/swing/JButton.html} to work with a Java-button. But you can also use the Scala-equivalent \textit{scala.swing.Button}\footnote{http://www.scala-lang.org/api/current/scala/swing/Button.html}. This two button-types will provide nearly the same functionality.

 So what is the idea of creating a nearly similar library a second time? Why have the Scala-developers done such extra work? The answer is, that they have tried to improve and simplify the usage of the Swing-library(and many other libs too!). So big parts of this Scala-Libraries are just Wrapper-objects, Wrapper-Classes and Wrapper-Methods of already existing parts in Java-Libraries. Needless to say that they also added new useful shapes and functionality.