Category Archives: Isabelle

Isabelle/VSCode 1.0 in Isabelle2017

The new Isabelle2017 release includes support for VSCode as alternative Prover IDE front-end. This continues earlier experiments and is released as Isabelle/VSCode 1.0. Note that Isabelle/jEdit had its 1.0 release in October 2011 and is presently at version 9.0.

Isabelle2017 provides the main Isabelle/Scala/PIDE functionality to connect to VSCode, using the official Language Server Protocol (with some PIDE add-ons). The front-end requires the extension called “Isabelle2017” from the VSCode marketplace: its README provides more information and installation instructions.

The Isabelle/VSCode project has been made possible thanks to funding by Aesthetic Integration (Grant Passmore and Denis Ignatovich).

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Isabelle Docker image

The new Isabelle2017 distribution provides a Docker image via the Docker Hub repository.

The Docker image contains Ubuntu Linux with Isabelle2017. It can be used, e.g. on another Linux host like this:

  • docker pull makarius/isabelle:Isabelle2017
  • docker run makarius/isabelle:Isabelle2017

That provides command-line access to the regular isabelle tool wrapper, with indirection through the Docker container infrastructure.

The image already contains ML heaps for Isabelle/Pure and Isabelle/HOL. Here is an example to build more:

  • docker run makarius/isabelle:Isabelle2017 -s -b HOL-Library

Note that Docker is mainly for command-line tools on the “Cloud”. There is presently no Isabelle Prover IDE support, although very old-fashioned X11 connections can be made to work with extra tinkering.

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Release candidates for Isabelle2017

We are heading towards the Isabelle2017 release, which is scheduled for October 2017. This spot provides a reference for upcoming release candidates.

  • Isabelle2017-RC0 (15-Aug-2017): informal snapshot for early experimentation. See also AFP/c98eb24b3598.
  • Isabelle2017-RC1 (03-Sep-2017): first official release candidate; almost everything ready, but some documentation still needs update. See also AFP/c7574e891704.
  • Isabelle2017-RC2 (08-Sep-2017):
    • improved Nunchaku model finder: now in Main HOL;
    • more HOL-Analysis material;
    • clarified dependencies of theory HOL-Library.Monad_Syntax;
    • robustification and fine tuning of Isabelle/jEdit.

    See also AFP/dfb6f8bc70e3.

  • Isabelle2017-RC3 (23-Sep-2017):
    • Isabelle/VSCode: improved treatment of Unicode vs. Isabelle symbols.
    • Documentation for “isabelle imports” in system manual.
    • Update of Isabelle/jEdit documentation.
    • Update of E prover and CVC4 for 32bit platforms.
    • Fine-tuning and polishing.

    See also AFP/dcf4dc3a3594.

As usual, the Isabelle release process is subject to the laws of causality: release candidates can be modified, but the final release is unchangeable. This means that testing needs to happen in the weeks before the final release, not after it.

The main forum for discussion of Isabelle2017 release candidates is on isabelle-users mailing list.

Update 09-Oct-2017: The final release of Isabelle2017 (October 2017) is now available from the Isabelle website. The above release candidates will disappear eventually.

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The Isabelle Prover IDE after 9 years of development, and beyond

On Mon 24-Jul-2017, I gave a presentation at the BigProof event in Cambridge. Title: The Isabelle Prover IDE (PIDE) after 9 years of development, and beyond. Abstract:

The main ideas around Isabelle/PIDE go back to summer 2008. This is an overview of what has been achieved in the past 9 years, with some prospects for the future. Where can we go from here as Isabelle community? (E.g. towards alternative front-ends like Visual Studio Code; remote prover sessions “in the cloud”; support for collaborative editing of large formal libraries.) Where can we go as greater ITP community (Lean, Coq, HOL family)?

Here are some notable VSCode projects that were briefly mentioned in the talk:

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Social Networks in the Isabelle and Coq community

Here is an interesting (draft) paper about Social Network structures in the Isabelle and Coq community, based on the main mailing lists of the two systems:

J. Fleuriot, S. Obua, Ph. Scott: Social Network Processes in the Isabelle and Coq Theorem Proving Communities. arXiv:1609.07127, September 2016.

Just a few comments of mine:

  • The isabelle-users mailing list is still the main forum for Isabelle users, but Stackoverflow is gaining more and more importance. Note that I helped to bring it in form in Mar-2013 (earning a badge for 30 days of continuous activity :-), but I am rarely participating there now, because I am too busy with the classic mailing lists.
  • The seasonal peaks on isabelle-users in Fig. 1 are due to the release process, which happens approx. every 8-10 months. In 2012, I started to make discussion of release candidates fully public on isabelle-users; before it was confined to isabelle-dev, which is also open to everyone, but has fewer participants.
  • Page 12: “This seems to indicate that there is some clear separation of expertise when it comes to the tool.” This is correct and follows a general principle of Isabelle development: there are areas of undisputed “experts” for certain parts of the system. Thus there is a clear responsibility to make that thrive in the long term. Often this assignment is a consequence of starting that area in the first place, or investing significant work in upgrading it (e.g. by a designated PhD or research project). My recurring appearance on Sledgehammer threads is mainly technological: I am responsible for underlying infrastructure for parallel ML programming and the Prover IDE; it also overlaps with overall system integration and release management due to the add-on ATP and SMT systems.
  • In recent years, I have economized my appearance on isabelle-users as follows:
    1. Incoming messages are marked as important, when the topic overlaps with my areas of expertise. I rarely answer on the spot.
    2. After some days, weeks, or months, I revisit marked message and make sure that questions are actually answered, or add a few remarks to discussion threads.
    3. During the release candidate phases, I revisit all marked messages back to the previous release (or even one before that), to make sure that old technical problems are solved or remain in a reasonably well-defined state.

    This means the mailing list also serves as an “issue tracker”. I’ve made some experiments with an explicit tracker just for the release process, but there was very little participation. Trackers tend to become a long-term storage for well-known and unresolved problems.

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Visual Studio Code as Prover IDE for Isabelle

Microsoft is more and more becoming an Open Source company, e.g. it has joined the Linux foundation as Platinum member in November 2016. A notable Open Source project by Microsoft is Visual Studio Code: under the slogans “Code editing. Redefined. Free. Open Source. Runs everywhere.” it provides a very interesting editor framework, as a desktop application based on Node.js and TypeScript.

The prover community has already started to support this emerging successor of vi and Emacs, e.g. see Coq Support for Visual Studio Code and the Lean for VSCode.

Isabelle/VSCode is now following this trend: I have spent some weeks in December 2016 / January 2017 with VSCode, using a little bit of TypeScript and implementing the new Language Server Protocol in Isabelle/Scala. The subsequent screenshot shows formal annotations produced by Isabelle/PIDE in the usual manner, while the editor rendering is all done by VSCode. For more information, see the report Isabelle/VSCode in January 2017.

The Isabelle/VSCode project was funded by Aesthetic Integration (AI). See also my article about a talk at ITP 2016 by Grant Passmore (co-founder of AI).

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Foundations of Higher-Order Logic at Curry Club Augsburg

On Thu 01-Dec-2016 there will be a presentation about “Foundations of Higher-Order Logic with Classical Reasoning and Hilbert-Choice” at Curry Club Augsburg.

Start: approximately 19:00
Duration: approximately 90min
Language of the talk: German

Overview:

  • History of Higher-Order Logic
  • Implementations of HOL
  • Quasi-programming in Isabelle/HOL
  • Isabelle foundations: primitive inferences, object-logic rules, rule composition, structured proofs
  • Foundations of Higher-Order Logic: actual Isabelle/HOL, Pure bootstrap of HOL
  • Isabelle theory with some exercises (for Isabelle2016-1)

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Release candidates for Isabelle2016-1

The coming Isabelle2016-1 release is scheduled for December 2016. This spot is continuously updated to inform about the ongoing process of testing release candidates.

  • On 07-Oct-2016 an informal snapshot Isabelle2016-1-RC0 was published.
  • On 28-Oct-2016 the release candidate Isabelle2016-1-RC1 was published. Serious testing by users is now required, to expose remaining problems.
  • On 06-Nov-2016 the release candidate Isabelle2016-1-RC2 was published. Various details have been consolidated.
  • On 22-Nov-2016 the release candidate Isabelle2016-1-RC3 was published. More fine points have been consolidated. A component for the new experimental Nunchaku tool has been included.
  • On 27-Nov-2016 the release candidate Isabelle2016-1-RC4 was published. It introduces the following important last-minute changes:
    1. Prover IDE: more aggressive flushing of machine-generated input
    2. Sledgehammer: MaSh is faster and less likely to hang seemingly forever
    3. fine-tuning of Isabelle/LaTeX typesetting
  • On 08-Dec-2016 the release candidate Isabelle2016-1-RC5 was published, presumably the last one. It introduces the following important last-minute changes:
    1. more uniform automatic indentation (empty vs. non-empty lines)
    2. fewer tracing/warning messages in some proof tools

The Isabelle release process is subject to the laws of causality: release candidates can be modified, but the final release remains final. Testing needs to happen in the weeks before the final release, not after it.

The main forum for discussion of Isabelle2016-1 release candidates is on isabelle-users mailing list.

Update 13-Dec-2016: The final release of Isabelle2016-1 (December 2016) is now available from the Isabelle website. The above release candidates will disappear eventually.

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Isabelle/PIDE as IDE for ML

On Friday 18-Nov-2016 10:00, I will give a presentation about PIDE at Laboratoire de Recherche en Informatique, Orsay (Paris Sud).

Abstract:

Isabelle is usually positioned as environment for interactive and automated theorem proving, but its Prover IDE (PIDE) may be used for regular program development as well. Standard ML is particularly important here, since it is the bootstrap language of Isabelle/ML (i.e. SML with many add-ons) and Isabelle/Pure (i.e. the logical framework).

The ML IDE functionality of Isabelle + Poly/ML is manifold:

  • Continuous feedback from static analysis and semantic evaluation is already available for years, e.g. Isabelle2014 (August 2014). It is a corollary of how PIDE interaction works, and of the integration of the Poly/ML compiler into that framework. Source files are statically checked and semantically evaluated while the user is editing. The annotated sources contain markup about inferred types, references to defining positions of items etc.
  • Source-level debugging within the IDE is new in Poly/ML 5.6, which is bundled with Isabelle2016 (February 2016). The Prover IDE provides the Debugger dockable to connect to running ML threads, inspect the stack frame with local ML bindings, and evaluate ML expressions in a particular run-time context. See also here.
  • IDE support for the Isabelle/Pure bootstrap process is new technology for the coming release of Isabelle2016-1 (December 2016). The ROOT.ML file acts like a quasi-theory in the context of theory ML_Bootstrap: this allows continuous checking of all loaded ML files. The theory file is presented with a modified header to import Pure from the running Isabelle instance.
  • It is also possible to modify standalone SML projects, to edit the sources freely in the ML IDE. For example, MetiTarski can participate after some trivial changes of its ROOT.ML file.

Overall, we move more and more to an integrated framework for development of formal-reasoning tools, but other applications are admissible as well.

The Slides are available, together with their sources (which are required for the live system demo).

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