[DSRP Evidence](https://dsrpevidence.org/)

# Compositional Generator Equivalence

Vandikas et al., 2026, Proceedings of the ACM on Programming Languages (ICFP) — Computer Science & AI

Patterns: [Distinctions](https://dsrpevidence.org/pattern/distinctions), [Systems](https://dsrpevidence.org/pattern/systems)

## In short

Whether a generator's whole behavior can be soundly justified from a coarse composition of its parts, versus needing the fine-grained whole, is a parts-whole systems question, and the proof turns on a hard line between the two granularities of semantics.

## What they found (results)

The authors prove that Hedgehog's standard generator semantics is non-compositional, that any sound-and-complete compositional semantics for it must collapse to the fine-grained sampling semantics, and introduce a restricted language, Hedgehog->, that does admit a genuinely compositional semantics, implemented and evaluated in Haskell.

These researchers were not testing DSRP. The finding is theirs; the correspondence to DSRP is drawn by this site.

[Source](https://doi.org/10.1145/3828695)