Issues

• Raw/unredered logo image in documentation

  bug
  typelevel/cats-mtl#738 · Filter by author tommorris opened on Oct 18, 2026

• "unspecified error" when Handle.allow refers to a local singleton object

  typelevel/cats-mtl#676 · Filter by author kubukoz opened on Jan 12, 2026

• Logo image is rendered incorrectly by Laika

  typelevel/cats-mtl#671 · Filter by author satorg opened on Dec 22, 2025
  1

• Raises and Handles aliases on Scala 3?

  typelevel/cats-mtl#666 · Filter by author armanbilge opened on Nov 21, 2025
  1

• Surfacing submarines

  typelevel/cats-mtl#660 · Filter by author durban opened on Oct 21, 2025

• Handle.allow(F) and (Applicative|Monad)Throw appear to be incompatible.

  typelevel/cats-mtl#652 · Filter by author morgen-peschke opened on Sep 30, 2025
  1

• Handle creates a black-box when Submarine escapes rescue

  typelevel/cats-mtl#648 · Filter by author morgen-peschke opened on Sep 15, 2025

• Are cats.mtl.Handle[F[_], E] and cats.ApplicativeError[F[_], E] the same abstraction?

  typelevel/cats-mtl#646 · Filter by author benhutchison opened on Sep 9, 2025
  4

• Ergonomics of Raise need improvement

  typelevel/cats-mtl#645 · Filter by author benhutchison opened on Sep 8, 2025
  7

• Would writing type ErrS[F[_]] = Handle[F, String] inside Cats MTL be doing the ecosystem a favour?

  typelevel/cats-mtl#644 · Filter by author benhutchison opened on Sep 8, 2025

• Rebranding Cats MTL to emphasize the Capabilities, not the Monad Transformers

  typelevel/cats-mtl#516 · Filter by author benhutchison opened on Aug 5, 2023
  13

• handle error with partial function

  typelevel/cats-mtl#444 · Filter by author prophe05 opened on Sep 2, 2022

• Can't migrate from v0.7: StateT[EitherT, ...], ...] vs. EitherT[StateT, ...], ...]

  typelevel/cats-mtl#305 · Filter by author marcinzh opened on Jan 25, 2021
  1

• New typeclass to run reader-like effects

  typelevel/cats-mtl#287 · Filter by author FunFunFine opened on Nov 30, 2020
  1

• Inductive instances over ContT

  good first issuehelp wanted
  typelevel/cats-mtl#227 · Filter by author djspiewak opened on Jun 1, 2020
  4

• Add a cats-mtl-free submodule

  typelevel/cats-mtl#226 · Filter by author djspiewak opened on Jun 1, 2020

• Hand-write (or scalafix) syntax stuff

  good first issue
  typelevel/cats-mtl#225 · Filter by author djspiewak opened on May 31, 2020

• Write a ton of documentation

  good first issuehelp wanted
  typelevel/cats-mtl#222 · Filter by author djspiewak opened on May 31, 2020
  4

• FunctorListen doesn't understand nested Monad stack

  typelevel/cats-mtl#180 · Filter by author thobson opened on Jan 13, 2020

• Consider facility to view State as Reader

  typelevel/cats-mtl#179 · Filter by author benhutchison opened on Jan 11, 2020
  7

• Bracket for MTL

  typelevel/cats-mtl#135 · Filter by author iRevive opened on Aug 5, 2019
  2

• Explore a submodule for more performant instances.

  enhancementtriage
  typelevel/cats-mtl#80 · Filter by author LukaJCB opened on Sep 30, 2018
  2