paul-buerkner/brms

Consider replacing `asym_laplace_*` with native version from Stan?

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#1,836 opened on Nov 13, 2025

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Stanefficiencygood first issue

Description

Stan since 2.28 has natively adopted Asym Laplace and named skew double exponential distribution.

Perhaps it would speed up the sampler by using the native version for asym_laplace family?

Contributor guide

Tech stack
r
Domain
datamachine learning
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
R programmingStan knowledgebrms package structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Investigate the current implementation of `asym laplace *` functions in the brms source code (likely in `R/` or `src/`). Compare with the native Asymmetric Laplace distribution added in Stan 2.28. Check the brms documentation and any related issues or PRs. The goal is to replace the custom implementation with a call to the native Stan function, potentially improving sampler speed. Further clarification from maintainers on desired approach and compatibility requirements is needed.