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VsCoq is an extension for Visual Studio Code (VS Code) and VSCodium which provides support for the Coq Proof Assistant. It is built around a language server which natively speaks the LSP protocol.

Supported Coq versions

VsCoq supports all recent Coq versions >= 8.18. If you are running an Coq < 8.18 you should use VsCoq Legacy.

Installing VsCoq

To use VsCoq, you need to (1) install the VsCoq language server and (2) install and configure the VsCoq extension in either VS Code or VSCodium.

Installing the language server

After creating an opam switch, pin Coq, and install the vscoq-language-server package:

$ opam pin add coq 8.18.0
$ opam install vscoq-language-server

After installation, check that you have vscoqtop in your shell and note the path to this executable:

$ which vscoqtop

Pre-release versions

We often roll out pre-release versions. To get the correct language server version please pin the git repo. For example, for pre-release v2.1.5:

$ opam pin add vscoq-language-server.2.1.5  https://github.com/coq/vscoq/releases/download/v2.1.5/vscoq-language-server-2.1.5.tar.gz

Installing and configuring the extension

To install the VS Code or VSCodium extension, first run code or codium. Then press F1 to open the command palette, start typing "Extensions: Install Extension", press enter, and search for "vscoq". Switch to the pre-release version of the extension and enable it. Finally, go to the extension settings and enter the vscoqtop full path from above in the field "Vscoq: Path".

If you want asynchronous processing of Coq files, you can go to the "Proof: Mode" and select "Continuous". Otherwise, processing will step by step and top-down as in VsCoq1.

Pre-release versions

In VsCode, from the extensions page, either use the drop down menu from the Uninstall button and select Install another version, or click on Switch to pre-release.

Troubleshooting

Known problems

• Getting an Unable to start coqtop or coqtop-stderr: Don't know what to do with -ideslave error. This is a known issue if you are updating from a very old version. Solution: navigate to your extensions folder (Extensions: Open Extensions Folder from the command palette) and then delete the siegbell.vscoq-**version** folder.

• Extension hanging: query panel shows a loading bar and shortcuts fail This could be due to an old vscode version. Make sure vscode is up to date.

Getting help

If you are unable to set-up vscoq, feel free to contact us on the Vscoq devs and users channel in zulip.

Features

• Syntax highlighting
• Asynchronous proof checking
• Continuous and incremental checking of Coq documents

The new version of vscoq allows users to opt for continuous checking, see the goal panel update as you scroll or edit your document.

By default vscoq is configured to use classic step by step checking mode.

• Customisable goal panel

Users can choose their preferred display mode, see goals in accordion lists...

... Or organized in tabs.

• Dedicated panel for queries and their history

We now support a dedicated panel for queries. We currently support Search, Check, About, Locate and Print with plans to add more in the future.

• Messages in the goal panel

We also support inline queries which then trigger messages in the goal panel.

• Supports _CoqProject

Since version 2.1.7

• Outline

We now support a document outline, which displays theorems and definitions in the document.

• Ellipsis for the goal panel

Goals can now be ellided. First through the "vscoq.goals.maxDepth" setting which ellides a goal if the display becomes to large. Finally by clicking on the goal view as showcased here. The following modifiers can be used:

• Alt + Click: open/close an ellipsis (only opens partially).
• Shift + Alt + Click: fully open an ellipsis (all children are also opened).

• Quickfixes (only for Coq >= 8.21)

We have added support for quickfixes. However, quickfixes rely on some Coq API which will only make it in the 8.21 release. Developpers are encouraged to list and add their own quickfixes in the Coq source code.

• Block on first error

We support the classic block on error mode, in which the execution of a document is halted upon reaching an error. This affects both checking modes (Continuous and Manual). A user can opt out of this execution mode by setting it to false in the user settings.

Settings

After installation and activation of the extension:

(Press F1 and start typing "settings" to open either workspace/project or user settings.)

Coq configuration

• "vscoq.path": "" -- specify the path to vscoqtop (e.g. path/to/vscoq/bin/vscoqtop)
• "vscoq.args": [] -- an array of strings specifying additional command line arguments for vscoqtop (typically accepts the same flags as coqtop)
• "vscoq.trace.server": off | messages | verbose -- Toggles the tracing of communications between the server and client

Memory management (since >= 2.1.7)

• "vscoq.memory.limit: int -- specifies the memory limit (in Gb) over which when a user closes a tab, the corresponding document state is discarded in the server to free up memory. Defaults to 4Gb.

Goal and info view panel

• "vscoq.goals.display": Tabs | List -- Decide whether to display goals in separate tabs or as a list of collapsibles.
• "vscoq.goals.diff.mode": on | off | removed -- Toggles diff mode. If set to removed, only removed characters are shown (defaults to off)
• "vscoq.goals.messages.full": bool -- A toggle to include warnings and errors in the proof view (defaults to false)
• "vscoq.goals.maxDepth": int -- A setting to determine at which point the goal display starts elliding. Defaults to 17. (since version >= 2.1.7)

Proof checking

• "vscoq.proof.mode": Continuous | Manual -- Decide whether documents should checked continuously or using the classic navigation commmands (defaults to Manual)
• "vscoq.proof.pointInterpretationMode": Cursor | NextCommand -- Determines the point to which the proof should be check to when using the 'Interpret to point' command.
• "vscoq.proof.cursor.sticky": bool -- a toggle to specify whether the cursor should move as Coq interactively navigates a document (step forward, backward, etc...)
• "vscoq.proof.delegation": None | Skip | Delegate -- Decides which delegation strategy should be used by the server. Skip allows to skip proofs which are out of focus and should be used in manual mode. Delegate allocates a settable amount of workers to delegate proofs.
• "vscoq.proof.workers": int -- Determines how many workers should be used for proof checking
• "vscoq.proof.block": bool -- Determines if the the execution of a document should halt on first error. Defaults to true (since version >= 2.1.7).
• "vscoq.proof.display-buttons": bool -- A toggle to control whether buttons related to Coq (step forward/back, reset, etc.) are displayed in the editor actions menu (defaults to true)

Code completion (experimental)

• "vscoq.completion.enable": bool -- Toggle code completion (defaults to false)
• "vscoq.completion.algorithm": StructuredSplitUnification | SplitTypeIntersection -- Which completion algorithm to use
• "vscoq.completion.unificationLimit": int -- Sets the limit for how many theorems unification is attempted

Diagnostics

• "vscoq.diagnostics.full": bool -- Toggles the printing of Info level diagnostics (defaults to false)

For extension developers

See Dev docs

Maintainers

This extension is currently developed and maintained by Enrico Tassi, Romain Tetley.

License

Unless mentioned otherwise, files in this repository are distributed under the MIT License.

The files client/syntax/coq.tmLanguage and client/coq.configuration.json are also distributed under the MIT License, Copyright (c) Christian J. Bell and contributors.