httpuv
httpuv ships almost nothing, which is what you want from the web server under Shiny
Comparison · DevOps
promises vs vctrs
A side-by-side editorial comparison of promises and vctrs — release velocity, themes, recent moves, and the top alternatives to consider.
Shared themes:performance
promises vs vctrs: 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 vctrs?
vctrs 0.7 moved conditional recoding down into the tidyverse type system.
vctrs defines the type and size rules underpinning the tidyverse. Its 0.6.x line was pure maintenance — CRAN-requested C changes, R-devel test fixes, ALTREP performance. Version 0.7.0 broke that pattern with a family of conditional and recoding functions that duplicate dplyr verbs at lower cost.
promises vs vctrs: 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.
vctrs
0.0DEVOPS
vctrs 0.7 moved conditional recoding down into the tidyverse type system.
◆ Current state
vctrs defines the type and size rules underpinning the tidyverse. Its 0.6.x line was pure maintenance — CRAN-requested C changes, R-devel test fixes, ALTREP performance. Version 0.7.0 broke that pattern with a family of conditional and recoding functions that duplicate dplyr verbs at lower cost.
◆ Where it's heading
The package is absorbing operations that previously lived in dplyr, implementing them once against the shared type rules so every consumer inherits consistent semantics. Releases since have tightened attribute handling in vec_restore() and cleared non-API C usage that R's checking tools now flag.
◆ Prediction
Expect more tidyverse verbs to acquire vctrs-level implementations, and continued removal of non-API C usage as R narrows what packages are permitted to call.
Alternatives to promises and vctrs
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 vctrs.
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
httr
httr's last releases are housekeeping - the package now points users at httr2
magrittr
magrittr rewrote its pipe in C, then base R shipped one and the releases stopped
See all promises alternatives → · See all vctrs alternatives →
Recent activity from promises and vctrs
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 3mo agovctrsvctrs 0.7.3 removes a non-API PRVALUE() usage
- 4mo agovctrsvctrs 0.7.2 clears unrecognized attributes in vec_restore()
- 6mo agovctrsvctrs 0.7.1 fixes protection issues found by rchk
- 6mo agovctrsvctrs 0.7.0 adds vectorized if-else and case-when ⚡
- 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
- 2y agovctrsvctrs 0.6.5 adjusts C format strings for CRAN
- 2y agovctrsvctrs 0.6.4 fixes vec_c() performance with ALTREP vectors
- 3y agopromisesfuture_promise() returns early when workers are exhausted
Frequently asked questions
What is the difference between promises and vctrs?
Both compete on the same themes — performance — within DevOps. promises and vctrs 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 vctrs?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. promises and vctrs 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 vctrs?
Top vctrs alternatives in DevOps are ranked by recent ship velocity. Browse the "vctrs alternatives" section above for the current picks, or visit /alternatives/vctrs for the full list with editorial commentary on each.