Any help from the community to assist in resolving these points is greatly appreciated!

Here follows the changelog for 0.10.0. I also wrote up an informal migration guide.

Added

• Support for zero-copy parsing (i.e: parser outputs that hold references to the parser input)
• Support for parsing nested inputs like token trees
• Support for parsing context-sensitive grammars such as Python-style indentation, Rust-style raw strings, and much more
• Support for parsing by graphemes as well as unicode codepoints
• Support for caching parsers independent of the lifetime of the parser
• A new trait, IterParser, that allows expressing parsers that generate many outputs
• Added the ability to collect iterable parsers into fixed-size arrays, along with a plethora of other container types
• Support for manipulating shared state during parsing, elegantly allowing support for arena allocators, cstrees, interners, and much more
• Support for a vast array of new input types: slices, strings, arrays, impl Readers, iterators, etc.
• Experimental support for memoization, allowing chumsky to parse left-recursive grammars and reducing the computational complexity of parsing certain grammars
• An extension API, allowing third-party crates to extend chumsky's capabilities and introduce new combinators
• A pratt parser combinator, allowing for conveniently and simply creating expression parsers with precise operator precedence
• A regex combinator, allowing the parsing of terms based on a specific regex pattern
• Properly differentiated ASCII and Unicode text parsers

Removed

• Parser::then_with has been removed in favour of the new context-sensitive combinators

Changed

• Performance has radically improved
• Error generation and handling is now significantly more flexible