An F* interactive mode for the atom editor
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This mode is now unmaitained and has fallen behind the development of F*

FStar Interactive Mode

An interactive mode for type-checking F* code, built as a package for the Atom editor. Package was originally adapted from atom-build.


  • You need a working F* binary that supports interactive mode (old binary releases of F* do not support this, so you might need to build from F* source)

    $ fstar.exe --in
    module Blah
  • You need an installation of Atom, and it's a good idea to also install atom-fstar separately for syntax highlighting.

  • Add to the $PATH variable the absolute path of the directory in which fstar.exe lives (normally $FSTAR_HOME/bin). You need to restart Atom after you make such changes.

  • Run apm install and apm link in the extension's directory.


In a F* buffer, pressing Ctrl+Shift+I will place a marker in the file and type-check the file from the previous marker (the start of the file, if there isn't one) until the current cursor.

Ctrl+Alt+G will jump to the next error, if any.

Ctrl+Alt+A will display all the errors.

Ctrl+Alt+C will kill the running background F* process. It's useful to do this to reset your state in case you observe odd behaviors.

Ctrl+Shift+N will type-check the file until the first (* check_marker *) comment (or to the current cursor, like Ctrl+Shift+I, in case there is no such marker).

Key bindings are platform-dependent: See the F* Interactive menu under Packages in Atom.