This release adds the lambda_calculus.terms.abc module containing predefined variables for all ASCII letters.

This release marks multiple things as final and performs some cleanup:

• mark Term subclasses as final
• mark predefined terms as final
• mark DepthFirstVisitor as final and add slots
• remove unused UnsafeSubstitution.free_variables

This release fixes the documentation build.

The release adds documentation hosted at Read the Docs.

This release corrects the README statement about recursive terms and adds a unit test to ensure they work.

This release adds common combinators and ISZERO to the terms subpackage.

This release improves the string representations of CollisionError

This release improves BetaNormalisingVisitor and the Visitors for variable substitution:

• BetaNormalisingVisitor now yields alpha conversions
• add Visitor to perform unchecked substitution to improve performance when possible
• add ABC for visitors which can be applied lazily
• refactored Visitors for variable substitution to use shorter class names

This release adds method chaining for term construction

This release fixes the license display on PyPI (again)