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Quick Start

Build Status Stories in Ready


HNC is buildable by both cabal sandbox and stack, on Windows, Linux and MacOS, in 64 or 32 bits.


stack update
stack setup
stack install
$(stack path --local-bin)/spl-hnc -O hn_tests/

Cabal sandbox

cabal update
cabal sandbox init
cabal install
.cabal-sandbox/bin/spl-hnc -O hn_tests/

Arch Linux

On Arch you can shorten build time by using prebuilt libraries from ArchHaskell project.

Add 2 ArchHaskell binary repositories (haskell-core and haskell-web) to pacman.conf. Install the following prebuilt packages from there to avoid building them. GHC comes as a dependency.

sudo pacman -S cabal-install haskell-{adjunctions,haskell-src-exts,hunit,logict,parsec,quickcheck,safe}

Proceed to the general compilation steps for Cabal sandbox described above

Advanced use

  • run tests (spl-test-hunit-exe is the primary suite)
  • read wiki
  • talk to me at
  • run our main test suite (dist/build/spl-test-hunit-exe/spl-test-hunit-exe)
  • run hnc with either -O or --dump-opt option to see our first attempts at optimization
  • follow instructions below to feed generated .cpp files to a C++ compiler and linker either directly or by using our extension to Boost.Build.

You'll need MSVC/GCC, Boost and Boost.Build.

Under the hood

HNC is an open-source cross-platform compiler based on modern technologies: Glasgow Haskell Platform, UUAGC attribute grammar preprocessor, Parsec parsing library, HOOPL graph optimization library, unification-fd structural unification library. The codebase is tiny: less than 4 KLOC, in the spirit of VPRI Ometa.

State of affairs

Many HN programs can already be compiled into an ugly functional subset of C++ and then into executables and run (see hn_tests folder for .hn sources and .cpp targets). A UDP echo server and a few Project Euler problems are the only useful programs so far, but mostly because we are too lazy to write more examples.

What is done

  • Parser
  • Type inference using UUAG, including injection of explicit template parameters when C++ doesn't infer them
  • Identifier- and scope-preserving translation from AST into graph IR and back using HOOPL dominator analysis
  • An optimizer of the IR using HOOPL (almost; only inlining and dead code elimination)
  • Compiler of closures into C++ functors using UUAG (almost)
  • C++ pretty printer (almost)
  • A Boost.Build plugin to integrate .hn files into C++ projects

Advances as of Mar 8 2017

  • Split Parser and Unifier into separate self-contained components
  • Joined efforts with and projects
  • Working on extracting other components to make HNC a sort of toy compiler construction framework
  • Working on loop generation

Advances as of Jul 21 2015

  • Fixed almost all optimizer bugs

What is not done

  • Proper error reporting
  • Assignments
  • The instantiator of polymorphic code into monomorphic is not implemented
  • Module system, namespace support, HNI implementation and C++ integration in general are rudimentary or missing
  • Priorities of C++ infix operators are broken
  • RAII should be used with care
  • SPL support is almost missing
  • Polymorphic constants like “empty list” are not supported

Setting up MSVC and Boost

  • Install free Visual C++ Express or non-free Visual Studio
  • Download Boost library from
  • Extract boost subfolder from the distribution. It's the folder containing header files for all libraries.

Create config.cmd one level above HNC folder, so it's not under source control:

@set INCLUDE=folder-containing-boost-subfolder
@call "%VS100COMNTOOLS%..\..\VC\vcvarsall.bat"

VS100COMNTOOLS is environment variable name set by VC 10.0 installer. Use set | findstr COMN to find out which version(s) of Visual C you have installed and change the .cmd file accordingly.

run testAll.cmd from hn_tests folder. You should see tmp-*.cpp files being generated from .hn sources and compiled into .obj files.

Setting up GCC

The generated code is not specific to MSVC or Windows, so any other Boost-compatible C++ compiler and platform should work too. However, the scripts to run test suite are not there yet.

To run deref1.cpp test manually with GCC, run

gcc -I../cpplib/include test.cpp ../cpplib/lib.cpp -lstdc++ --std=c++0x

from hn_tests folder if Boost headers are installed globally to /usr/include, or

gcc -I../cpplib/include -Ifolder-containing-boost-subfolder test.cpp  ../cpplib/lib.cpp -lstdc++ --std=c++0x

if Boost headers are manually unpacked locally.


Distributed under GNU Lesser General Public Licence Version 3.

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