Weeknotes 2026-W06 › Project Pterodactyl: incremental architecture (opens in new tab)

In my spare time I have been continuing to work out the architecture for incremental query-based elaboration on the CAS model. One bit of received wisdom in this area is the “green tree / red tree” distinction, inherited from Roslyn. Green trees are concrete syntax trees that carry no positioning information (except textual length of nodes); red trees are an ephemeral structure that is layered on top of the green tree, and carries absolute positions as well as other useful things. Red trees a...