zarr-python
Zarr's package split keeps producing standalone tools: a server, now a lazy indexer.
Comparison · DevOps
promises vs withr
A side-by-side editorial comparison of promises and withr — release velocity, themes, recent moves, and the top alternatives to consider.
Shared themes:performance
promises vs withr: at a glance
What is promises?
promises drops R6 for plain environments and wires async work into OpenTelemetry
promises supplies the async primitives behind Shiny and plumber. After years of small domain and future() fixes, the last two releases changed both what a promise costs and what it can report: 1.4.0 corrected nested domain ordering and added the first OpenTelemetry integration, and 1.5.0 replaced the R6 promise class with a classed environment while stabilizing the tracing API.
What is withr?
withr rebuilt defer() on base R's own on.exit(), and got much faster for it
withr provides the with_ and local_ functions that temporarily change global state and restore it on exit - the cleanup primitive under most of the tidyverse test suites. Version 3.0.0 reimplemented defer() as a thin wrapper over base::on.exit(), which the maintainers made possible by contributing the required arguments to R 3.5 itself. Everything since has been small correctness work.
promises vs withr: editorial side-by-side
promises
0.0DEVOPS
promises drops R6 for plain environments and wires async work into OpenTelemetry
◆ Current state
promises supplies the async primitives behind Shiny and plumber. After years of small domain and future() fixes, the last two releases changed both what a promise costs and what it can report: 1.4.0 corrected nested domain ordering and added the first OpenTelemetry integration, and 1.5.0 replaced the R6 promise class with a classed environment while stabilizing the tracing API.
◆ Where it's heading
Two things are being fixed at once. Promise domains - the mechanism that carries context across async boundaries - have been the source of nearly every bug in this window, and they are now being used deliberately as the vehicle for tracing rather than just for error handling. Meanwhile the object itself is being made cheap enough to create in volume.
◆ Prediction
Expect the OpenTelemetry surface to lose its experimental label and pick up the same span coverage Shiny would need end to end; the deprecated ospan function names should be removed in a following release.
withr
0.0DEVOPS
withr rebuilt defer() on base R's own on.exit(), and got much faster for it
◆ Current state
withr provides the with_ and local_ functions that temporarily change global state and restore it on exit - the cleanup primitive under most of the tidyverse test suites. Version 3.0.0 reimplemented defer() as a thin wrapper over base::on.exit(), which the maintainers made possible by contributing the required arguments to R 3.5 itself. Everything since has been small correctness work.
◆ Where it's heading
The arc here is a package pushing its own machinery down into base R and then living off the result. Once defer() became on.exit(), the remaining work is about where cleanup is allowed to happen - knitr documents, source() calls, the global environment, session end - and about restoring state correctly when an expression exits early. Releases are now infrequent and CRAN-driven.
◆ Prediction
Expect continued low-volume releases fixing edge cases in where deferred handlers run; with the core delegated to base R, there is little left that would prompt a larger change.
Alternatives to promises and withr
Other DevOps products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either promises or withr.
ellipsis
ellipsis' checks live in rlang now; the package is a compatibility shim.
clock
clock is turning calendar conventions lubridate hard-coded into parameterized types.
httpuv
httpuv ships almost nothing, which is what you want from the web server under Shiny
htmltools
htmltools spends three releases walking back its own fill-layout opinions
xml2
xml2 relicensed to MIT, then moved its hot accessors from S3 into C
See all promises alternatives → · See all withr alternatives →
Recent activity from promises and withr
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 1mo agowithrlocal_seed() actually preserves the seed now
- 9mo agopromisesOpenTelemetry spans across async work; R6 dropped for environments ⚡
- 9mo agopromisesNested promise domains fixed; then() gains a tee argument
- 1y agopromisesRealigns future object creation with the future package
- 1y agopromisesFixes stack overflow on long promise chains
- 1y agopromisesFixes domains forgotten inside nested handlers
- 1y agowithrlocal_language() no longer warns when set to C
- 2y agowithrdefer() becomes a thin wrapper over base::on.exit() ⚡
- 3y agopromisesfuture_promise() returns early when workers are exhausted
- 4y agowithrCleanup works inside Rmd and source(); with_() gains a getter
- 4y agowithrNew maintainer; handlers run at session end
- 5y agowithrlocal_options() can set NULL; with_seed() controls RNG kind
Frequently asked questions
What is the difference between promises and withr?
Both compete on the same themes — performance — within DevOps. promises and withr are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is promises better than withr?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. promises and withr are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). For your specific use case, the alternatives sections above list other DevOps products to evaluate alongside.
What are the best alternatives to promises?
Top promises alternatives in DevOps are ranked by recent ship velocity. Browse the "promises alternatives" section above for the current picks, or visit /alternatives/promises for the full list with editorial commentary on each.
What are the best alternatives to withr?
Top withr alternatives in DevOps are ranked by recent ship velocity. Browse the "withr alternatives" section above for the current picks, or visit /alternatives/withr for the full list with editorial commentary on each.