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VM and tracing JIT for Haskell (work in progress)
Haskell C++ C Python Assembly Shell



Lambdachine is virtual machine for Haskell which uses a trace-based JIT compiler. Lambdachine consists of two components:

  • lcc: A bytecode compiler that uses GHC to compile Haskell to Lambdachine bytecode files.

  • lcvm: The virtual machine which loads bytecode files and executes it.


Lambdachine currently only supports the pure subset of Haskell. User-defined datatypes and operations on integers and characters are supported, but mutable references, arrays, or I/O operations are not yet supported. The runtime system is single-threaded and no concurrency primitives are supported.


You need:

  • GHC 7.8 compiled with integer-simple for integers
  • A C++ compiler, either g++ or clang

All dependencies are on Hackage and can be installed via cabal,

Installation steps:

  1. Configuring

    $ ./boot   # Creates ./configure script
    $ ./configure   # Autodetect ghc, ghc-pkg, g++, etc.

    This will only find binaries in your $PATH. You can specify a specific version of ghc and a matching ghc-pkg by passing them as arguments to the configure script, e.g.,

    $ ./configure --with-ghc=${HOME}/code/ghc/head/inplace/bin/ghc-stage2 \
  2. Building

    $ make install-deps
    $ make boot
    $ make

This should build the bytecode compiler lcc, the test suite and the actual VM, called lcvm. To run the test suite use:

$ make check

See for more targets. The benchmarks are in directory tests/Bench/. Benchmarks use the C preprocessor to compile a version for GHC and another for Lambdachine. For example, to build the benchmark SumFromTo1 use:

$ make bench-ghc/SumFromTo1
$ ./bench-ghc/SumFromTo1 +RTS -s -A1m    # run it
$ make tests/Bench/SumFromTo1.lcbc     # also built by "test" target
$ ./lcvm -e bench Bench.SumFromTo1

For benchmarking, make sure to build lcvm with full optimisations. To do so, edit your mk/ file to contain the following line:


Each benchmark has code for two versions: a test version and a benchmark version. By default, the test target is used. To run a benchmark, you have to explicitly specify to use bench as the entry point. This is what the -e option does.

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