Two concrete demonstrations of the composition architecture:
THIRD DOMAIN (proves step 8's "a new domain is just a dict + leaf, no new control flow").
host/comp-deps folds a composition to the object ids it TRANSCLUDES — the static contains
DAG of a body. It reuses host/comp-fold's seq/alt/each dispatch verbatim; only the leaf
(collect `(ref ID)`) + accumulator (concat) are new. Useful in its own right (what a
(seq (ref c0) (each … (ref …))) body pulls in; context-specific — alt picks the taken
branch). compose suite 20/20.
LIVE EXECUTE-FOLD DEMO (makes step 7 tangible, parallel to /compose-demo for render).
/workflow-demo runs ONE composition object's :body through host/exec-run — the SAME structure
the render-fold would turn into HTML, folded by execute into a plan of effects (validate →
branch on status → notify each recipient). host/blog-seed-workflow-demo! + host/blog-workflow-
demo + route + serve.sh seed. Shows the behaviour model IS an execute-fold over a composition
object — the same object the block editor authors. blog suite 165/165.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The roadmap's capstone: now that two folds exist (render, execute), extract the machinery
they share. host/comp-fold (compose.sx) is the reusable core — the seq/alt/each combinator
dispatch + the `when` predicate set (host/comp--pred?) + the context-environment + the `each`
source (host/comp--source) + recursion + the depth guard, ALL in one place. A domain plugs in
via a small dict {:empty :combine :leaf :overflow}; only its leaves and how results combine
differ:
render = {:empty "" :combine str …} leaf -> markup (+ row/grid layout combinators)
execute = {:empty (list) :combine concat …} leaf -> effect
host/comp-render and host/exec-run are now one-liners over host/comp-fold with their domain.
execute.sx shed its own seq/alt/each dispatch — it's just a dict + a leaf. A THIRD domain
(eval/reduce/extent over the same algebra) is now only a new dict + leaf, no new control flow.
Both folds went through the core with ZERO behaviour change: new tests/compose.sx exercises
the core + render domain directly (17/17 — leaves, seq, row, alt+when (has/eq/not), each
(items/query/empty), tmpl recursion over a (children) tree + depth guard, ref transclude, one
object two contexts); execute 13/13; blog 162/164 (2 pre-existing relate-picker fails). Full
host conformance 388/390. Wired tests/compose.sx into conformance.
plans/composition-objects.md roadmap steps 1-8 COMPLETE.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
