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id: design: Roc library imports for worlds — pure dependencies and platform-dependent dependencies #5956
Description
Part of the worlds design program: #5955. Statements S1–S4 of the 2026-11-04 brief.
Requirement (Drew, in substance)
Design how more advanced Roc libraries work for worlds, in detail:
- Worlds must, at a minimum, be able to import pure dependencies.
- Worlds may also be allowed to import whatever dependencies they want — how far this goes is an open design question, not a default yes.
- A dependency may rely on platform capabilities and therefore be technically not pure, yet still be importable by a world/app. The import system has to represent that honestly: a library's purity is a function of the platform surface it touches, not a binary label the author asserts.
Open questions
- How does a Roc package declare the platform functions it uses, and how does the world compiler check that set against the compiling platform's catalog (
pkgs/id/crates/id-core/src/world_caps.rs) at import time? - Do platform-dependent libraries resolve against the world's platform, or do they carry their own platform requirement that must be a subset of the world's?
- What is the failure mode and error quality when an import's platform needs exceed the platform (see the demo task's negative tests)?
- Where do imported libraries come from: URL, registry, upload — and how does that interact with the library typing design in the taxonomy child of #5955?
Related
- Core/app platform design: #2028
- Roc libraries shipped Phases 9–10, verification debt: #796
- Capability-provider parent: #5686
Done looks like
A design doc section (or standalone doc) covering: import resolution, platform-requirement representation for libraries, subset checking against the platform catalog, and error behavior — sufficient to implement the demo task without further design decisions.
Activity
developing-today commentedon Nov 5, 2026
CODE-1622
dezren39 commentedon Nov 5, 2026
Wave-2 tie-in (conversation archaeology, findings F7 + F10) — start from what shipped.
pkgs/id/crates/id-core/src/world_caps.rs(time.now/tick, random.u64, players(.list), chat.say/history, records.read, schedule.at/cancel, world.info + modules Key, Screen, RocJson, RocGrid, RocCap, RocText), and imports are checked against the world's ceiling at compile time. No file or network capability exists in the catalog today.Record:
workspace/scratch/worlds-capabilities-brief-2026-11-04/conversation-tie-ins.md(F7, F10).dezren39 commentedon Nov 5, 2026
Wave-2 follow-ups filed from the prior-art research (Lane B). Granular sub-scopes of this issue, each carrying the relevant research findings + citations:
Research source:
workspace/scratch/worlds-capabilities-brief-2026-11-04/prior-art-research.md. Full wave-2 mapping:workspace/scratch/worlds-capabilities-brief-2026-11-04/wave2-map.md.