Dhall for python

Pure python implementation of dhall language.

Work in progres

python setup.py build  # to patch the grammar and compile parser tables
python setup.py test  # to run tests
flake8  # to lint the code
make abnf_patch  # to make changes to dhall.abnf persistent

Status

• [x] parsing

  All tests from acceptance test suite pass, except AST is not checked against CBOR.

• [ ] typechecking / evaluating / normalizing

  Some tests from acceptance test suite pass, but typechecking infrastructure needs to be havily reworked.

• [ ] import resolution

• [ ] loading from / dumping to binary

• [ ] (pretty)printing expressions

  There is some code responsible for printing for type errors explanation, but it's incomplete and does not properly support precedence.

Details

Parsing is done using parglare GLR parser library. grammar.abnf from dhall-lang repository is first patched, then converted into GLR parser tables. Take a look at setup.py, how it's done.

Acceptance tests comes from dhall-lang repository. They are then triggered during unit testing using awesome parametrized package. Take a look at tests/test_acceptance.py.

To check what dhall-python is capable of parsing call something like

cat dhall-haskell/tests/parser/annotations.dhall | dhall-python-parse