Wren: A Fast Logic Programming eDSL With Host Language Garbage Collection

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" summary

Wren is a Scala LP eDSL that reworks term representation and execution to piggyback on host language garbage collection, using typed terms/goals so unification is opt‑in and allowing nondeterministic construction of native objects. Implementation uses a weak‑reference trail for backtracking and replaces allocation-heavy streams with iterators over streams to cut temporary allocations. Evaluation across the largest miniKanren-style benchmark suite shows up to three orders of magnitude speedups versus the fastest LP eDSL and occasional wins over SWI‑Prolog, plus much lower heap usage.

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" chapters (12)

1. 0:00Wren introduction
2. 1:05Embedding logic programming
3. 3:54MiniKanren challenges
4. 4:14Typed terms interface
5. 9:51Memory retention in unification
6. 11:56Backtracking with weak refs
7. 14:25GC for unused variables
8. 16:11Optimizing with iterators
9. 17:55Term interconversion
10. 19:01Benchmarking Wren
11. 25:28Future directions
12. 26:14Q&A