Example projects (#242)

This adds a list of example applications.

Question: is _Design_ the best place for this?

Closes #68

content/docs/learn/design/projects.md

@@ -0,0 +1,46 @@
+---
+title: Example projects
+sidebar_position: 5
+description: Bigger projects where the design guidelines are put into practice
+---
+
+# Example projects
+
+Here are some projects which use Arrow and follow the design guidelines. The purpose is showcasing these techiques in bigger applications; docs require small examples for comprehension, but sometimes they don't give the full picture that one of these complete applications can.
+
+## [Real World](https://github.com/nomisRev/ktor-arrow-example)
+
+[Real World](https://medium.com/@ericsimons/introducing-realworld-6016654d36b5) is a blogging platform that has been purposedly created to highlights the possibilities of each language and ecosystem. The linked implementation uses:
+
+- [Ktor](https://ktor.io/) as HTTP framework.
+- [SQLDelight](https://cashapp.github.io/sqldelight) for database access.
+- [Kotest](https://kotest.io/) for property-based testing.
+
+## [Functional Quiz](https://github.com/TevJ/kfp-quiz)
+
+Service to create an answer quizzes, written in a functional style. Apart from Arrow, this project uses:
+
+- [http4k](https://www.http4k.org/) as HTTP framework.
+- [Exposed](https://github.com/JetBrains/Exposed) for database access.
+
+## [Weather App](https://github.com/serras/WeatherApp)
+
+Small weather forecast application built with [Compose Multiplatform](https://www.jetbrains.com/lp/compose-multiplatform/) Desktop.
+
+- [Ktor Client](https://ktor.io/docs/getting-started-ktor-client.html) to perform HTTP requests.
+- [Kotest](https://kotest.io/) for property-based testing.
+  - [Turbine](https://github.com/cashapp/turbine) to test ViewModels.
+
+## GitHub Alerts
+
+This application manages subscriptions to GitHub repository events, and turns them into Slack messages. It is architected as a series of microservices which communicate using [Apache Kafka](https://kafka.apache.org/)
+message queues, by means of [kotlin-kafka](https://github.com/nomisRev/kotlin-kafka) and
+[Avro4k](https://github.com/avro-kotlin/avro4k).
+
+The same project is available using two different sets of technologies.
+
+- The [Ktor version](https://github.com/47deg/gh-alerts-subscriptions-kotlin) uses [Ktor](https://ktor.io/) as HTTP framework.
+  - [Cohort](https://github.com/sksamuel/cohort) for health checks,
+  - [Tegral](https://tegral.zoroark.guru/docs/modules/core/openapi/ktor) for generating OpenAPI specs.
+  - [SQLDelight](https://cashapp.github.io/sqldelight) for database access.
+- The [Spring version](https://github.com/xebia-functional/gh-alerts-subscriptions-kotlin-spring) uses the [Spring](https://spring.io/) modules for Kotlin.