arXiv subjects

Rafaello Sanna

Publications and source records attributed to Rafaello Sanna.

3 recordsLinked to original sources

arXiv2026

chrKanren: Constraint Handling Rules in a Relational Language

We present chrKanren, a dialect of the purely relational constraint logic programming language miniKanren which includes support for Constraint Handling Rules (CHR), a language for writing rule-based programs such as constraint solvers. We show how to integrate CHR's constraint propagation mechanism into the language of miniKanren search streams such that both processes remain complete. We also use chrKanren to illustrate novel applications of constraints in miniKanren, such as semantic unification of user-defined data structures and type-and-example-directed synthesis for relational interpreters in the style of MYTH.

cs.PL↗

arXiv2025

Beyond Cons: Purely Relational Data Structures

We present {Kanren} (read: set-Kanren), an extension to miniKanren with constraints for reasoning about sets and association lists. {Kanren} includes first-class set objects, a functionally complete family of set-theoretic constraints (including membership, union, and disjointedness), and new constraints for reasoning about association lists with shadowing and scoped lookup. These additions allow programmers to describe collections declaratively and lazily, without relying on structural encodings and eager search over representation spaces. The result is improved expressiveness and operational behavior in programs that manipulate abstract data -- particularly interpreters -- by supporting set equality based on contents, enabling finite failure. We describe the design and implementation of {Kanren} in a constraint-enabled miniKanren system and illustrate its use in representative examples.

cs.PL↗

arXiv2021

Fast Nonblocking Persistence for Concurrent Data Structures

We present a fully lock-free variant of the recent Montage system for persistent data structures. Our variant, nbMontage, adds persistence to almost any nonblocking concurrent structure without introducing significant overhead or blocking of any kind. Like its predecessor, nbMontage is buffered durably linearizable: it guarantees that the state recovered in the wake of a crash will represent a consistent prefix of pre-crash execution. Unlike its predecessor, nbMontage ensures wait-free progress of the persistence frontier, thereby bounding the number of recent updates that may be lost on a crash, and allowing a thread to force an update of the frontier (i.e., to perform a sync operation) without the risk of blocking. As an extra benefit, the helping mechanism employed by our wait-free sync significantly reduces its latency. Performance results for nonblocking queues, skip lists, trees, and hash tables rival custom data structures in the literature -- dramatically faster than achieved with prior general-purpose systems, and generally within 50% of equivalent non-persistent structures placed in DRAM.

cs.DC↗