Repository Issues

typelevel/cats

Lightweight, modular, and extensible library for functional programming.

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Stars
 (5,438 stars)
Forks
 (1,241 forks)
Indexed issues
 (9 indexed issues)
open beginner issues
 (9 open beginner issues)
Latest indexed
Jul 5, 2026
Last GitHub push
May 11, 2026
License
Other
Contributing guide
Contributing guide
Code of conduct
Code of conduct
Dominant language
Scala
PR merge metrics
 (Avg merge 4h 2m) (5 merged PRs in 30d)
Beginner labels
help wantedgood first issue

Issues

9 open indexed issues

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Open
Make `Hash.fromUniversalHashCode` null safe
good first issue

typelevel/cats #4,831 opened Feb 22, 2026 · Scala · 5,438 stars

Why recommendedHas a beginner-friendly label · Contributing guide available
Has a beginner-friendly labelContributing guide available
6 comments1 reaction1 assignee
Open
typeclass-based collections implementations
enhancementhelp wanted

typelevel/cats #4,147 opened Mar 9, 2022 · Scala · 5,438 stars

Why recommendedNo assignee yet · Has a beginner-friendly label
No assignee yetHas a beginner-friendly labelContributing guide available
28 comments2 reactions0 assignees
Open
Clean out warnings from Dotty
good first issuelsug

typelevel/cats #3,751 opened Jan 30, 2021 · Scala · 5,438 stars

Why recommendedNo assignee yet · Has a beginner-friendly label
No assignee yetHas a beginner-friendly labelContributing guide available
2 comments0 reactions0 assignees
Open
Add a documentation page on error handling
documentationhelp wanted

typelevel/cats #3,523 opened Jul 16, 2020 · Scala · 5,438 stars

Why recommendedNo assignee yet · Has a beginner-friendly label
No assignee yetHas a beginner-friendly labelContributing guide available
8 comments3 reactions0 assignees
Open
Add `attemptOption` to Alternative
help wantedlow-hanging fruit

typelevel/cats #2,936 opened Jul 9, 2019 · Scala · 5,438 stars

Why recommendedNo assignee yet · Has a beginner-friendly label
No assignee yetHas a beginner-friendly labelContributing guide available
6 comments0 reactions0 assignees
Open
Improve doc for Func
documentationgood first issuehelp wantedlow-hanging fruitscope: small

typelevel/cats #2,650 opened Nov 30, 2018 · Scala · 5,438 stars

Why recommendedHas a beginner-friendly label · Contributing guide available
Has a beginner-friendly labelContributing guide available
8 comments0 reactions1 assignee
Open
Add doctests (excellent first-time issue)
documentationgood first issuehelp wanted

typelevel/cats #2,479 opened Sep 7, 2018 · Scala · 5,438 stars

Why recommendedNo assignee yet · Has a beginner-friendly label
No assignee yetHas a beginner-friendly labelContributing guide available
14 comments0 reactions0 assignees
Open
Style scaladoc slightly
documentationgood first issuehelp wanted

typelevel/cats #1,835 opened Aug 21, 2017 · Scala · 5,438 stars

Why recommendedNo assignee yet · Has a beginner-friendly label
No assignee yetHas a beginner-friendly labelContributing guide available
2 comments0 reactions0 assignees