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Verification system for effectful programs
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nikswamy Merge pull request #1695 from FStarLang/jay-mapmap
Introduce [map_val] to [FStar.Map]
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.ci restore Dec 16, 2017
.completion removing uses of --verify_module in our makefiles ***NO_CI*** Oct 27, 2017
.docker Update Dockerfile Apr 16, 2019
.hooks Revert "[CI] regenerate hints + ocaml snapshot" Jan 27, 2017
.scripts fix git invocation Dec 12, 2018
bin Makefile: keep a copy of the F#-built F* in bin/ Jan 9, 2019
contrib/CoreCrypto/fst copyright notice on all .fst and .fsti files that lacked them Nov 12, 2018
doc [CI] regenerate hints + ocaml snapshot Apr 11, 2019
examples [CI] regenerate hints + ocaml snapshot Apr 21, 2019
ucontrib Documented how to satisfy the OpenSSL dependency on Arch Mar 29, 2019
ulib Merge branch 'master' into jay-mapmap Apr 23, 2019
.gitattributes Updated contributiosn Nov 12, 2018
.gitignore adding .dump to gitignore Feb 17, 2019
.gitmodules removing openssl submodule Feb 15, 2018
.ignore Un-ignore some hand-written files Aug 17, 2017
.merlin First attempt at replacing OCaml prettyprinters with a single one May 15, 2018
.travis.yml Revert "[CI] regenerate hints + ocaml snapshot" Jan 27, 2017 typo Apr 9, 2019 Update Nov 12, 2018
LICENSE-fsharp.txt Revert "[CI] regenerate hints + ocaml snapshot" Jan 27, 2017
Makefile Giving some love to KReMLin and Vale Mar 29, 2019
_tags As discussed May 15, 2018 Fix build_local script Mar 5, 2019
version.txt Bump version number to May 18, 2018

F*: An ML-like language aimed at program verification

Build status

F* website

More information on F* can be found at




The F* tutorial provides a first taste of verified programming in F*, explaining things by example.


The F* wiki contains additional, usually more in-depth, technical documentation on F*.

Editing F* code

You can edit F* code using your favourite text editor, but Emacs, Atom, and Vim have extensions that add special support for F*, including syntax highlighting and interactive development. More details on editor support on the F* wiki.

Extracting and executing F* code

By default F* only verifies the input code, it does not compile or execute it. To execute F* code one needs to translate it for instance to OCaml or F#, using F*'s code extraction facility---this is invoked using the command line argument --codegen OCaml or --codegen FSharp. More details on executing F* code via OCaml on the F* wiki.

Also, code written in a C-like shalowly embedded DSL can be extracted to C or WASM by the KreMLin tool, and code written in an ASM-like deeply embedded DSL can be extracted to ASM by the Vale tool.

Chatting about F* on Zulip

Users can chat about F* or ask questions at (Zulip is a good open source alternative to Slack)

Community mailing list

The fstar-club mailing list is dedicated to F* users. Here is where all F* announcements are made to the general public (e.g. for releases, new papers, etc) and where users can ask questions, ask for help, discuss, provide feedback, announce jobs requiring at least 10 years of F* experience, etc.

List archives are public and searchable, but only members can post. Join here!

Reporting issues

Please report issues using the F* issue tracker on GitHub. Before filing please use search to make sure the issue doesn't already exist. We don't maintain old releases, so if possible please use the online F* editor or directly the GitHub sources to check that your problem still exists on the master branch.


The F* for the masses blog is also expected to become an important source of information and news on the F* project.


This new variant of F* is released under the Apache 2.0 license; see LICENSE for more details.

Towards F* version 1.0

This is a new variant of F* (carrying version 0.9.x) that is still in development and we hope will eventually lead to a 1.0 release. This new variant is incompatible and quite different compared to the previously released 0.7 versions and earlier.

Old F* versions (v0.7.1 and earlier)

F* v0.7.1 and earlier are no longer maintained, so please do not create any issues here about those versions.

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