Canopy in March 2026 — Highlights
A two-minute summary of a month of work. For the day-by-day version, see the Japanese original.
Canopy is a structure editor written in MoonBit: it treats source code as structure (IR) rather than strings, with text kept as the source of truth. Concurrent editing is built on a CRDT implementing the eg-walker paper. Around it sit a few sibling projects: Loom (incremental parsing), incr (incremental computation), and js_engine (a JS interpreter validated against test262).
1. The parser becomes loom
The parser that had lived inside Canopy since December moved out to become its own repository, dowdiness/loom, with Canopy migrating onto the new API. This is the first of several libraries that would go on to grow independently of Canopy over the following months.
2. SyncEditor unifies editing
ParsedEditor was replaced by SyncEditor, folding editing, undo/redo, sync, and presence into a single editor abstraction — the foundation everything from Lambda name resolution to the later block/JSON editors would build on.
3. Rabbita and the Ideal editor take off
A Rabbita-based projectional editor got a real UI foundation this month: performance problems were fixed, and mobile layout, design tokens, and tree-pane navigation landed. Sixteen structural editing actions shipped too — the first broad set of “verbs” for editing a program’s structure directly instead of its text.
4. CRDT performance gets serious
FugueTree/traverse_tree went iterative, an order-tree was introduced, and a two-count retreat optimization made event-graph-walker traversal 17.7× faster — the kind of unglamorous work that keeps structural editing fast enough to not notice.
5. Real-time collaboration over WebSocket
A transport layer, relay server, sync-recovery protocol, and an ephemeral-presence store (v2) landed, giving Canopy the first real infrastructure for more than one person editing the same document live.
6. Framework extraction begins, new editors debut
ProjNode[T] went generic, TreeNode/Renderable traits appeared, and the first framework/core packages were carved out of Canopy-specific code. On top of that groundwork, a block editor, a JSON editor, an AST zipper, and the first phase of a “Container” block-document abstraction all shipped.
March set up almost every thread the rest of the year pulls on: loom as an independent parser library, a generic projection framework, and block-based editors reaching beyond Lambda.
- GitHub: dowdiness/canopy · dowdiness/loom · mooncakes.io/user/dowdiness
- Full log: March 2026 devlog (Japanese)