A Vim mode for FStar
Vim script Python
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.


VimFStar Interactive

VimFStar Interactive is a Vim plugin for F*, an ML-like language with a type system for program verification.



You can use your favorite pathogen-compatible plugin manager to install VimFStar.

If you're using vim-plug, for example, perform the following steps to install VimFStar:

  1. Edit your .vimrc and add a Plug declaration for VimFStar.

    call plug#begin()
    " ...
    Plug 'FStarLang/VimFStar', {'for': 'fstar'}
    " ...
    call plug#end()
  2. Restart Vim

  3. :PlugInstall to install the plugin.

Use of the interactive verification

Note: Interactive mode requires a Cygwin build of (g)Vim.

First, put fstar.exe in your $PATH. VimFStar will check that fstar.exe is present before loading interactive functions.

To test your code and it to the environment up to the current position of the cursor, press <F2> in normal mode. The marker v is set to the line just after the end of the checked part, so you can go there with 'v. If you already know that your code is correct until the cursor and just want to add it to the context, you can press <F6> for a quick test (useful for projects with thousands of lines and where normal tests last very long).

If you want to test some part of your code without adding it to the environment, select it in visual line mode (Shift+V) and press <F2>

If you want to get the result of the test you launched, press <F3> in normal mode

If you want to see again the errors sent by F*, press <F4>

If you are working on a big chunk of code, and it has no empty new line inside, you can try to select it quicker with <F5> in order to check it with <F2>. You can go back to where you were with <CTRL-o><CTRL-o>

You can reset the interaction with the command :Freset in case something went wrong or if you want to change a checked part.

If you want to use library files and/or set options, use build-config in your file. For example, if my file is at $FSTAR_HOME/examples/metatheory and I want to use classical.fst and ext.fst in $FSTAR_HOME/lib and set some options, I will put the following code at the top of my file:

    options:--z3timeout 20 --max_fuel 8 --max_ifuel 6 --initial_fuel 4 --initial_ifuel 2;
    other-files:../../lib/classical.fst ../../lib/ext.fst

This configuration is read when the buffer is loaded or when the plugin is reset. So do not forget to reset the plugin if you change build-config.


VimFStar is distributed under the same license as Vim itself. See LICENSE for more details.

Planned Improvements

  • more accurate syntax highlighting.
  • syntastic integration.
  • better highlighting of verified code
  • quick access to error locations
  • ability to pop environment