---
title: "Syntactic Control of Interference"
authors:
  - "John C. Reynolds"
year: 1978
venue: "POPL"
arxiv: null
doi: "10.1145/512760.512766"
source: "https://doi.org/10.1145/512760.512766"
topics:
  - plt
  - capabilities
seed_rank: 158
seed_batch: "prefill-2026-08-13"
reviewed: "2026-08-13"
pool: "languages"
relevance_score: 9
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---

# Syntactic Control of Interference

## One-sentence takeaway

Reynolds gives syntactic restrictions that make interference between program phrases visible in the type structure, so aliased active use of the same storage cannot hide behind ordinary application.

## Why it matters here

Safe parallel ECS mutation is this problem: two systems that both write a component must be treated as interfering phrases, and the type/capability layer should refuse to compose them the way SCI refuses to compose interfering λ-terms.

## Key ideas

- Interference is not just alias analysis after the fact; it is a property of how phrases may share assignable storage.
- Passive phrases may be aliased freely; active phrases that write storage may not be used in interfering combination.
- The type system distinguishes these classes so illegal sharing is a type error rather than a runtime race.
- Procedure application is the dangerous combinator: passing the same writable cell to two active parameters is the canonical banned pattern.
- The paper is the ancestor of later capability, separation, and disjointness type systems for controlled mutation.

## Caveats

## Links

- DOI: [10.1145/512760.512766](https://doi.org/10.1145/512760.512766)