Standing plan (most concrete — #beginners "property based testing", 2024-08-28):
PBT should be builtin to the compiler + expect, not a bolt-on library. Plan discussed:
- Start minimal: basic generators, with an auto-derived Arbitrary implementation the same way Roc auto-derives Encoders/Decoders (Richard Feldman, Brendan Hansknecht).
- Design it so it can later plug into a real fuzz engine for deeper testing — open question was bundling a fuzz engine (Go-style) vs. making it easy to plug in an external one.
- Luke Boswell suggested filing a GitHub issue to preserve the intent for future contributors.
- No PBT support exists yet — today you can only fake it with a hardcoded seed + manual randomness.

#compiler-development "Property testing and fuzzing" (2024-01-29, revisited 2025-08):
- Brendan wrote a design doc surveying property testing/fuzzing options for Roc, and built a prototype roc-fuzz using libFuzzer with an Arbitrary-style generator.
- Richard preferred Roc eventually build its own coverage instrumentation rather than depend on LLVM's, and floated fuzzing effects by auto-generating fake host I/O.
- 2025 follow-up: a contributor (Johan Lövgren) said this thread inspired a master's thesis on fuzzing + PBT, sharing lessons about generators baking in false assumptions.