arrow-kt/Category-Theory-for-Programmers.kt

Kotlin sample code for Bartosz Milewski's Category Theory for Programmers

Contributing

Contributions (PR, review, issues) are welcome! If you are interested, please indicate that you are working on in the respective issues. You can find the issues for each chapter here here.. Feel free to claim an issue you want to work on by adding a comment. Someone will then move it to In progress in the project board

We discuss Arrow and development of FP in general in Kotlin in the Kotlin Community Slack in the arrow and arrow-contributors channels.

Build the project with:

./gradlew runAnk

Spaces and indentation

Please use 2 spaces to indent your code.

Type-check your code

Use ```kotlin:ank:silent``` for code that is compilable, use ```kotlin``` otherwise.

Use a line of ............. to separate between code examples.

functions vs. methods

If it's a "standalone" function, use the function syntax, i.e.

val f: (A) -> B

If it is inside an interface or class, use the method, i.e.

fun f(a: A) : B

Λnk

• The Docs for Λnk without ank:playground

• If you define / redefine type classes please define them within a playground environment.

```kotlin:ank:playground
import arrow.core.ForListK
import arrow.core.ListK
import arrow.Kind
import arrow.core.fix
import arrow.typeclasses.Functor

interface ListKFunctor : Functor<ForListK> {
    override fun <A, B> Kind<ForListK, A>.map(f: (A) -> B): ListK<B> =
        fix().map(f)
}
```... 

Playground Docs. But for now a basic set-up as the snippet above is sufficient. Remember that ank:playground wont make the code snippet global for other snippets.

• In some instances (in the context of coroutine examples) Λnk won't process very long (over ~160 lines) md files. Split them up into < chapter >-Part1.md , < chapter >-Part2.md

• Debug with (optionally add the --stacktrace)

   ./gradlew runAnk

Initial drafts 🎉

Now there are initial drafts for the missing sections!

It's only necessary to add the translation in Kotlin after the existing snippets in Haskell.

Pick the draft from drafts directory and move it to src/main/ank directory to be considered when building the project.

Even the hypothetical file for Scala is included as a help in drafts/scala so it's possible to add the translation in Kotlin with more information:

Please, note that each snippet has ```kotlin:ank:silent``` by default. Replace it by just ```kotlin``` or ```kotlin:ank:playground``` for different purposes according to this documentation.

License

This work is licensed under a Creative Commons Attribution 4.0 International License.