Issues

• alterFinsertWith rewrite rule leaves a thunk when inserting an absent key into a strict HashMap

  bug
  haskell-unordered-containers/unordered-containers#599 · Filter by author sjakobi opened on Jul 24, 2026

• Try replacing the assertions in Array.hs with -fcheck-prim-bounds

  blocked-on:GHCmaintenance
  haskell-unordered-containers/unordered-containers#588 · Filter by author sjakobi opened on Feb 23, 2026
  4

• Idea for reducing array allocations in functions that use shrink

  performance
  haskell-unordered-containers/unordered-containers#587 · Filter by author sjakobi opened on Jan 19, 2026
  3

• Represent empty maps as BitmapIndexed 0 []?!

  performance
  haskell-unordered-containers/unordered-containers#578 · Filter by author sjakobi opened on Dec 14, 2025
  6

• Some type constraints can be relaxed from Hashable to Eq

  maintenance
  haskell-unordered-containers/unordered-containers#574 · Filter by author sjakobi opened on Dec 11, 2025 · 0.3

• Iterating arrays from right to left might be faster

  performance
  haskell-unordered-containers/unordered-containers#561 · Filter by author sjakobi opened on Nov 29, 2025
  3

• hashNub (and hashNubOn)

  feature-request
  haskell-unordered-containers/unordered-containers#560 · Filter by author sjakobi opened on Nov 29, 2025
  21

• Projects that use u-c?

  haskell-unordered-containers/unordered-containers#555 · Filter by author sjakobi opened on Nov 26, 2025
  2

• Make use of hashable's Hashed type?!

  feature-request
  haskell-unordered-containers/unordered-containers#552 · Filter by author sjakobi opened on Nov 15, 2025
  6

• Add upsert?!

  compatibility-with-containersfeature-request
  haskell-unordered-containers/unordered-containers#549 · Filter by author sjakobi opened on Nov 13, 2025
  4

• Review time complexities of difference[With[Key]]

  documentation
  haskell-unordered-containers/unordered-containers#543 · Filter by author sjakobi opened on Nov 9, 2025

• Improve instance Ixed (HashMap k a) in lens

  feature-request
  haskell-unordered-containers/unordered-containers#541 · Filter by author sjakobi opened on Nov 2, 2025
  1

• Make Array unlifted?!

  maintenanceperformance
  haskell-unordered-containers/unordered-containers#537 · Filter by author sjakobi opened on Oct 27, 2025
  1

• Inner go functions obfuscate the generated Core

  maintenance
  haskell-unordered-containers/unordered-containers#536 · Filter by author sjakobi opened on Oct 27, 2025

• indexOf allocates Maybes

  collisionsperformance
  haskell-unordered-containers/unordered-containers#534 · Filter by author sjakobi opened on Oct 25, 2025

• Size-hints and over-allocated arrays for fromList[With]

  feature-requestperformance
  haskell-unordered-containers/unordered-containers#532 · Filter by author sjakobi opened on Oct 22, 2025
  2

• Split Data.HashMap.Internal?!

  maintenance
  haskell-unordered-containers/unordered-containers#525 · Filter by author sjakobi opened on Oct 20, 2025

• union should make use of pointer equality

  performance
  haskell-unordered-containers/unordered-containers#522 · Filter by author sjakobi opened on Oct 18, 2025

• Compatibility with containers: restrictKeys

  compatibility-with-containersfeature-requestlow-hanging-fruitpr-welcome
  haskell-unordered-containers/unordered-containers#474 · Filter by author oberblastmeister opened on Jun 6, 2022
  3

• Feature request: traverseWithKey_

  feature-request
  haskell-unordered-containers/unordered-containers#470 · Filter by author sjakobi opened on May 23, 2022

• two and unionWithKey.goDifferentHash are very similar

  maintenance
  haskell-unordered-containers/unordered-containers#468 · Filter by author sjakobi opened on May 17, 2022
  1

• More Data.Map compatibility: Add insertLookupWithKey

  compatibility-with-containersfeature-request
  haskell-unordered-containers/unordered-containers#467 · Filter by author axman6 opened on May 16, 2022
  2

• instance Eq (HashMap k v) could use pointer equality

  performance
  haskell-unordered-containers/unordered-containers#466 · Filter by author sjakobi opened on May 15, 2022
  1

  

• u-c should use -msse4.2 by default

  performance
  haskell-unordered-containers/unordered-containers#464 · Filter by author sjakobi opened on May 13, 2022

• Towards unlifted HashMaps

  performance
  haskell-unordered-containers/unordered-containers#463 · Filter by author sjakobi opened on May 12, 2022
  9