typelevel / typelevel/cats

Infix operators for flatMap, coflatMap and cokleisli composition

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Dominant language
Scala
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Description

Cats already has the infix operator for Monad >>= which is very useful and expressive for chaing efectful functions.

Both haskell and scalaz also provide the fish operator >=> for kleisli composition, and also their right-to-left versions =<< and <=<

There are also the same operators for comonads: =>>, =>=, <<=, =<=

I would be glad to create a pull request for these if nobody objects.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reviewing Cats' existing Monad >>= operator and the requested fish and comonad operators in the issue. Locate the relevant typeclass and syntax entry points, then determine the tests needed to establish the intended left-to-right and right-to-left composition behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
backend
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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