F*: An ML-like language with a type system for program verification

F* website

More information on F* can be found at www.fstar-lang.org

Installation

See INSTALL.md

Tutorial

The F* tutorial provides a first taste of verified programming in F*.

License

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

Version 1.0

This is a new variant of F* that is still in development and we hope will lead to a 1.0 release soon. This new variant is incompatible and quite different compared to the previously released 0.7 versions.

Code structure

This section describes the general structure of the F* verifier.

Files

README.md: This file

INSTALL.md: Current installation instruction

setenv.sh:

A utility script that sets up the user's environment for running F*.

LICENSE-fsharp.txt:

The Apache 2.0 license of F# reproduced verbatim here. Most of the 
code in F* was written from scratch. However, some 1,330 lines
of source code were derived from F#, primarily in the lexer.

Directories

bin/

 Contains various binary files that the verifier uses. 

 It includes binaries for the FSharp.PowerPack, various
 utilities that the verifier uses internally. 

 All these binaries are available separately. 

 In order to use F*, you will need to download Z3 4.3.1 or 4.3.2
 binaries and place them in this directory (or somewhere in your
 path). You can fetch these binaries from z3.codeplex.com.

 F* should also be compatible with any theorem prover that implements
 the SMT2 standard (we use no Z3-specific features). So, you 
 should be able to use another solver by passing the 
 "--smt <path to solver exe>" option to F*.

examples/

 Around 22k lines of sample F* code, organized into various
 directories. All of these examples are provided as part of the
 the release so that our users have guidance on how to use the F*
 tool.

lib/

 Contains just two sample source files which are config files for
 the F* verifier.

src/

 All source code for the implementation of F* itself. 

 Makefile: A top-level file for building the verifier from source
           using the command line.
 
 VS/FStar.sln:
    A Visual Studio (2013) solution file for all the F* sources.

 fstar.fs: The top-level file in the source tree that launches the
           verification tool.

 basic/

    A directory containing various basic utilities used throughout
    the project.

    The following files, were adapted from the Apache 2.0 release
    of F#. Each of these files quotes F#'s license at the header.

    bytes.fs (derived from fsharp/src/absil/bytes.fs)
    range.fs (derived from fsharp/src/fsharp/range.fs)


 absyn/

    A directory definition various operations over the abstract
    syntax of F* programs. 


 parser/

    A directory defining a parser for F* concrete syntax into its
    abstract syntax. 

    The following files, were adapted from the Apache 2.0 release
    of F#. Each of these files quotes F#'s license at the header.

    lex.fsl (derived from fsharp/src/fsharp/lex.fsl)
    lexhelp.fs (derived from fsharp/src/fsharp/lexhelp.fs)

 tc/
 
    The main type-checker and verification condition generator.


 tosmt/
 
    A module that translates F*'s logical specification into the
    SMT2 language, the input of many SMT solvers, including
    Z3. Once this translation is done, it calls into the Z3
    binaries (needs to be available in your path) to verify that
    the logical spec is valid.

gdhuang/FStar