ekmett/lens

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Lenses, Folds, and Traversals - Join us on web.libera.chat #haskell-lens

Stars: 2.1k
Forks: 274
Open beginner issues: 0
Indexed issues: 78

Dominant language: Haskell
License: No license data
Last GitHub push: Aug 13, 2026
Latest indexed: Sep 15, 2026
Contributing guide: No contributing guide
Code of conduct: No code of conduct
Beginner labels: No beginner labels indexed
PR merge metrics: No merged PRs in 30d

Open All

78 open issues indexed

Do unification for Traversals constructed by makeLenses Open

enhancement lots of work template-haskell

ekmett/lens#56 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
makeFamily? Open

lots of work pie-in-the-sky

ekmett/lens#128 · 0 comments · 0 reactions · 1 assignee · Indexed Sep 15, 2026
Simplify TH configuration Open

api-change bikeshedding enhancement template-haskell

ekmett/lens#169 · 3 comments · 0 reactions · 1 assignee · Indexed Sep 15, 2026
Add `makeExposed`? Open

enhancement nuisance template-haskell

ekmett/lens#197 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
partsOf' inlines better than partsOf Open

performance

ekmett/lens#218 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Space leak in partsOf Open

performance

ekmett/lens#219 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Investigate trade-offs between the various `Leftmost`/`Rightmost` approaches. Open

api-change benchmark bikeshedding enhancement performance

ekmett/lens#245 · 3 comments · 0 reactions · 1 assignee · Indexed Sep 15, 2026
Should we change the API for holesOf? Open

api-change question

ekmett/lens#252 · 2 comments · 0 reactions · 1 assignee · Indexed Sep 15, 2026
QuasiQuoter for record construction Open

enhancement template-haskell

ekmett/lens#286 · 25 comments · 3 reactions · 0 assignees · Indexed Sep 15, 2026
A 'makeOptics' TH function that makes either Lenses or Prisms. Open

enhancement low priority template-haskell

ekmett/lens#373 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Deques Open

api-change bikeshedding low priority nuisance packaging

ekmett/lens#522 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
makeRecursiveFields Open

enhancement

ekmett/lens#550 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Adding strict functions Open

enhancement

ekmett/lens#574 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
A simple “zoom” which works in MonadState Open

enhancement

ekmett/lens#580 · 1 comment · 4 reactions · 0 assignees · Indexed Sep 15, 2026
Put together a tutorial we can collectively agree upon in `Control.Lens` Open

docfix enhancement high priority

ekmett/lens#587 · 0 comments · 0 reactions · 1 assignee · Indexed Sep 15, 2026
Benchmark moving the arguments to the right Open

benchmark easy performance

ekmett/lens#590 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
TH option for makePrisms to use HLists instead of tuples Open

enhancement packaging template-haskell

ekmett/lens#603 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
A straw man proposal - Control.Lens.Case for case analysis through prisms Open

enhancement

ekmett/lens#610 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
reorder parameters in makeClassy Open

api-change bikeshedding

ekmett/lens#625 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Potentially viable lens-core? Open

enhancement lots of work packaging question

ekmett/lens#647 · 16 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add a strict version of %~ Open

enhancement strictness

ekmett/lens#664 · 7 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
TH generation of prisms for GADTs in GHC 8 generates uncompilable prisms which are too general Open

lots of work template-haskell

ekmett/lens#684 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add ‘allEqualOf’ Open

bikeshedding easy enhancement

ekmett/lens#685 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add SurelyIxed class Open

bikeshedding enhancement

ekmett/lens#694 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Incorporate some flavor of one-off lens & prism construction via TH Open

accepted enhancement high priority

ekmett/lens#710 · 2 comments · 3 reactions · 0 assignees · Indexed Sep 15, 2026
Connection between *WithIndex and representable functors Open

api-change enhancement packaging

ekmett/lens#715 · 4 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Lack of functions which query with passthrough in monad Open

enhancement

ekmett/lens#719 · 5 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Infinite loop resulting from uniplate Open

ekmett/lens#742 · 10 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Laws of the -WithIndex classes Open

docfix

ekmett/lens#745 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add a function in Control.Lens.Plated to fold multiple plated things at once? Open

ekmett/lens#776 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add a shapely holesOf variant Open

feature-request

ekmett/lens#787 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add a class for certain indexed efficiencies Open

ekmett/lens#790 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
TH generation of Has instances for nested datatype with makeFields Open

ekmett/lens#805 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Change the naming convention of the "*Like" types Open

ekmett/lens#824 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add Zoom instance for FT Open

ekmett/lens#827 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
ASetter wants to leak space Open

strictness

ekmett/lens#863 · 5 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Document Zoom better Open

ekmett/lens#868 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Can non-simple fields be created with `makeLensesWith`? Open

ekmett/lens#875 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
Monadic tuple assignment operator Open

ekmett/lens#882 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
traverseOf_ is different from traverse_ Open

ekmett/lens#883 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Lifting isos through traversals Open

ekmett/lens#887 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Add sorting combinators? Open

ekmett/lens#892 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Cons and Snoc should require Each as a prerequisite. Open

ekmett/lens#900 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
zoom in monadic traversals (implement a Monad instance for Zooming) Open

packaging

ekmett/lens#908 · 6 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Typeclass for types which can be iterated under (->) Open

ekmett/lens#915 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Have prisms with ad-hoc classes for every field (equivalent to how `makeFields` generates lenses) Open

ekmett/lens#934 · 10 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
add support for "monadic modify state" Open

ekmett/lens#940 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 15, 2026
ix is able to insert undefined in strict (hash)map Open

ekmett/lens#944 · 12 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
Diagonal setters Open

ekmett/lens#975 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 15, 2026
IRC should be migrated from Freenode Open

ekmett/lens#979 · 3 comments · 2 reactions · 0 assignees · Indexed Sep 15, 2026

ekmett/lens

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