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A (Haskell DSL) stream language for generating hard real-time C code.
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STOP! The official Copilot repos are now at

Copilot: a stream DSL

Copilot is a stream (i.e., infinite lists) domain-specific language (DSL) in Haskell that compiles into embedded C. Copilot is similar in spirit to languages like Lustre. Copilot contains an interpreter, multiple back-end compilers, and other verification tools.


Copilot is comprised of a number of sub-projects which are automatically installed when you install Copilot from Hackage, as described below. (These are tracked as Git submodules in Copilot.)

  • copilot-language The front-end of Copilot defining the user language.

  • copilot-libraries User-supplied libraries for Copilot, including linear-temporal logic, fault-tolerant voting, regular expressions, etc.

  • copilot-core The core language, which efficiently represents Copilot expressions. The core is only of interest to implementers wishing to add a new back-end to Copilot.

  • copilot-cbmc A tool to generate a driver using CBMC, a third-party tool (see Dependencies below) that proves that the code generated by different C back-ends is equivalent. Currently, this includes the C99 back-end and the SBV back-end.

  • copilot-c99 A back-end that translates to Atom to generate hard real-time C code.

Optionally, you may which also to install

  • copilot-sbv Another back-end that translates to SBV, using its code generator to generate hard real-time C code as well. The ad

  • copilot-discussion Contains a tutorial, todos, and other items regarding the Copilot system.

Sources for each package are available on Github as well. Just go to Github and search for the package of interest. Feel free to fork!

Comments, bug reports, and patches are always welcome. Send them to leepike @


Please see the files under the Examples directory for a number of examples showing the syntax, use of libraries, and use of the interpreter and back-ends. The examples is the best way to start.


  • From Hackage:

    The Copilot library is cabalized. Assuming you have cabal and the GHC compiler installed (the Haskell Platform is the easiest way to obtain these), it should merely be a matter of running

         cabal install copilot

    with an Internet connection. Please see the INSTALL file for installation details.

  • From GitHub:

       git clone
       git submodule update --init
       make test

Once the installation is done, you can run the executable XXX which will execute the regression test suite for sbv on your machine.

Note there is a TravisCI build (linked to at the top of this README) if you have trouble building/installing.


copilot-cbmc depends on the C model-checker, CBMC. CBMC is a bounded model-checker for C code. We use CBMC to prove that two back-ends generating C generate semantically equivalent C, to help detect bugs in C back-ends.

Copyright, License

Copilot is distributed with the BSD3 license. The license file contains the BSD3 verbiage.


Copilot was developed, in part, with support from NASA's Aviation Safety Program, Contract #NNL08AD13T. Copilot was developed jointly by Galois, Inc. and the National Institute of Aerospace.

The following people have contributed to Copilot: Lee Pike, Nis Wegmann, Sebastian Niller, Robin Morisset, Alwyn Goodloe, and Levent Erkok.

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