P4229 R0 Canonical Parallel Scan: Expression and Observation Contracts for Reproducible Parallel Algorithms

[wg21bot]

P4229R0 Canonical Parallel Scan: Expression and Observation Contracts for Reproducible Parallel Algorithms (Andrew Drakeford)

[eisenwave]

This paper is requesting feedback from SG1 and SG6 based on its audience header and its contents, not from SG22.

[mattkretz]

P4229R0: Canonical Parallel Scan: Expression and Observation Contracts for Reproducible Parallel Algorithms

2026-06-11 SG6 Minutes

Chair: Matthias Kretz

Champion: Andrew Drakeford

Summary

• Too abstract for concrete feedback; Focus on selling the core idea and expand from there.
• Maybe consider abstracting a tree view onto a linear range for expressing reduction ordering.
• (How) does this idea relate to execution policies on existing algorithms? Could this be a more constrained par / par_unseq?

Polls

No polls were taken. The direction given to P4016R0 applies here as well.