Elm with OpenAPI

This small guide aims to explain how to use the OpenAPI Generator with Elm and to give some background on what is being generated.

OpenAPI is an initiative to standardise REST APIs. The OpenAPI Generator enable automatic generation of server interfaces, server stubs, clients (like the one for Elm) and documentation.

I do not want to go into details on the specification as that can be found on the official website.

A few advantages of working with OpenAPI are:

• It defines a clear contract between front-end and back-end, making it easier to collaborate;
• For Elm it means you no longer have to write your own JSON decoders & encoders as they can be generated automatically;
• It keeps your data transfer models uncoupled from your internal data models;
• It forces you to design your REST APIs in a language agnostic fashion;
• It enables easy refactoring as updating your specification will result in compile time errors on both server and client side;
• Your specification is also your (to be generated) documentation.