Building a GraphQL client in Elm For Elm

This presentation introduces
- Elm
- GraphQL
- Motivates why GraphQL is a good logical step as a data layer for Elm

Transcript

1. GraphQLing in Elm Application Engineer @ Hasura @k_rthik1991 Building a simple GraphQL client in elm
2. Elm
3. - Programming language for declaratively creating applications for the web - Purely functional - Statically typed - Immutable - Compiles to HTML, CSS, JS :)
4. Elm Architecture
5. Simple pattern for architecting web apps. Key focus is on code reuse, modularity and testing. It splits the application logic into three separate functions
6. - Model: Stores the state of the application - View: Renders the application on the UI - Update: Handles any user interaction and keeps the model and view in sync
7. Example
8. APIs
9. - Stateful applications require data to be stored at a secure location and be fetchable via API’s - Applications consume the API to service customer via a network call (async) - Options - SOAP - REST - ?
10. GraphQL
11. - Open source query and data manipulation language for API’s - It was developed by facebook in 2012 and made the spec and the reference implementation for javascript publicly available in 2015 - Designed with following principles - Strong typing - Introspective - Client specified queries etc..,
12. GraphQL addresses major drawbacks of REST APIs - Overfetching - Underfetching - Managing endpoints
13. Example
15. Why GraphQL in Elm?
16. - Elm as we learnt is a functional programming language with a strong type system. Using a language which is also designed with same set of principles goes well together. - GraphQL schema can be easily translated into Elm types and will prove to be a great data layer for Elm apps. - Resolves issues with data fetching and manipulation and ensures that if the program compiles, it works
17. Problem Statement
18. - GraphQL as it is can be used directly in elm program similar to rest by encoding the queries as strings and going through a series of data transformation to get the data into elm types for usage - The above approach will work but it will be at a cost a lot of repeated boilerplate code which can be easily abstracted and simplified.
19. In this talk we will look at - Key problems of using GraphQL directly - Explore ways on how we can improve the experience by abstracting key parts (query, mutation functions) using elm types. - We will then use it to interact with our GraphQL server
20. Key takeaways
21. - Learn Elm language and be able to build web applications using it - Have better understanding of Elm type system and how to write your own custom DSL to query GraphQL - Be in a position to evaluate GraphQL and/or Elm for your next project
22. Thank you!