The executable hgom takes a module consisting of several abstract datatypes declarations as an input and ouputs java classes. It is meant to mimic the java version of Gom: http://tom.loria.fr/wiki/index.php5/Documentation:Gom.

compiler, gpl, program, Propose Tags , java Gom, cabal-install, sloccount, gnuplot
cabal install hgom-0.6



Build Status

An haskell clone of the original java Gom code generator.


To compile hgom, install stack. Then run:

stack build

The hgom binary is generated in a directory displayed by stack. You can run it from there. Alternatively you can run it using stack exec hgom.


stack install

Running hgom

Run hgom --help to get some basic help. You can test the behaviour of hgom by running it as follows. Some examples are valid files, other ones demonstrate hgom error messages.

hgom examples/simple.gom
hgom examples/big.gom
hgom examples/many_errors.gom


Run the tests with:

stack test --test-arguments "-a N"

where N is the number of generated random inputs for each test case.

For a list of all possible test arguments check stack test --test-arguments "--test".


There is some benchmark in test/bench that generates bigger and bigger gom files and runs hgom and gom on them, measuring the gom/hgom ratio concerning the number of generated lines (using sloccount) and the elapsed time.

cd bench

It takes some time. The generated files can be plotted using gnuplot for instance.

Differences with gom


  • faster!
  • a far less permissive checker
  • smaller code, compiles much faster
  • almost 100% code coverage,
  • unit tests using QuickCheck, both on compiler data structures and generated code
  • regression tests for parser and checker
  • more things optional: visitable, checker, ...
  • toHaskell, makeRandom, depth and size methods generation (optional)
  • smaller code for some generated methods (string escaping factorized for instance)
  • faster code for some generated methods (less function calls, more constants)
  • faster parser (from*) methods: don't use an intermediate ATerm representation
  • pretty-printed generated code, optional compact (no indentation) option


  • no hooks
  • no ant task
  • imports only builtins
  • generates no comments


  • slightly different command-line arguments syntax