Builtins are part of the standard set
Make every Expression a ValueSemantics and use the known list of
attributes to map generically over any AST node.
Introduces a conditional, but removes boilerplate from every single
Internal flag to disable for acceptance tests from the standard (which
assume beta-only normalization in some cases). Otherwise, just always
alpha normalize as we go.
Update to latest binary format
Migrate to dhall-langv6.0.0
Use git-extras for `git root` in build
Bare minimum refactor to pass the metrics
Pass most compliance tests
No import or multiline string support yet
Beta normalization complete
Implement "shift" function for variable indices
All beta normalization except for functions