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ellipsis' checks live in rlang now; the package is a compatibility shim.
Comparison · DevOps
promises vs zarr-python
A side-by-side editorial comparison of promises and zarr-python — release velocity, themes, recent moves, and the top alternatives to consider.
promises vs zarr-python: 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 zarr-python?
Zarr's package split keeps producing standalone tools: a server, now a lazy indexer.
Zarr's Python implementation is being decomposed into standalone packages, with zarr-metadata for the model layer, zarr-indexing for index transforms and zarr-http-server for serving. Each ships on its own version line with its own changelog and documentation site. The most recent activity is zarr-indexing reaching 0.2.0 with LazyArray, followed by a fix to how subpackage docs are built.
promises vs zarr-python: 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.
zarr-python
6.3DEVOPS
Zarr's package split keeps producing standalone tools: a server, now a lazy indexer.
◆ Current state
Zarr's Python implementation is being decomposed into standalone packages, with zarr-metadata for the model layer, zarr-indexing for index transforms and zarr-http-server for serving. Each ships on its own version line with its own changelog and documentation site. The most recent activity is zarr-indexing reaching 0.2.0 with LazyArray, followed by a fix to how subpackage docs are built.
◆ Where it's heading
The split has moved past refactoring into producing capabilities Zarr did not previously have. zarr-http-server 0.1.0 put stores, arrays and groups behind HTTP, and zarr-indexing went from TensorStore-style index transforms in 0.1.0 to generic lazy indexing over the array API in 0.2.0. Supporting infrastructure is being built at the same pace, with towncrier changelogs and per-package docs, which is what the 0.2.1 docs fix is tidying.
◆ Prediction
Each extracted package has followed its 0.1.0 with a feature release within weeks, so the next move is most likely another zarr-indexing or zarr-http-server increment rather than a change to zarr-python itself.
Alternatives to promises and zarr-python
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 zarr-python.
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
withr
withr rebuilt defer() on base R's own on.exit(), and got much faster for it
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 zarr-python alternatives →
Recent activity from promises and zarr-python
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 1d agozarr-pythonSubpackage docs now build from the package directory
- 1d agozarr-pythonzarr-indexing 0.2.0: LazyArray brings lazy indexing to the array API
- 1d agozarr-pythonzarr_http_server-v0.1.0: HTTP server that exposes stores, arrays, groups (#3732) ⚡
- 13d agozarr-pythonzarr-indexing 0.1.0: TensorStore-style index transforms as a standalone package
- 14d agozarr-pythonzarr-metadata 0.4.0: model-layer changes and a standalone docs site
- 2mo agozarr-pythonzarr_metadata-v0.2.0: Widen ChunksLike type alias (#3990)
- 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
- 3y agopromisesfuture_promise() returns early when workers are exhausted
Frequently asked questions
What is the difference between promises and zarr-python?
They serve adjacent needs but don't currently overlap on shipped themes. zarr-python is currently shipping more aggressively (velocity 6.3 vs 0.0), with 1 editorial sparks in the last 30 days against 0. See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is promises better than zarr-python?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. zarr-python is currently shipping more aggressively (velocity 6.3 vs 0.0), with 1 editorial sparks in the last 30 days against 0. 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 zarr-python?
Top zarr-python alternatives in DevOps are ranked by recent ship velocity. Browse the "zarr-python alternatives" section above for the current picks, or visit /alternatives/zarr for the full list with editorial commentary on each.