At cca.io, we build mission-critical apps and services for the Public Transport and Public Safety industries. In 2018, we moved all our frontend development (web and React Native) to ReasonML.

As a case study about ReasonML in a finished product / client project, we present “Written Order”, a web app for Railway Safety. The app is an intelligent assistant for manual processes in train signalling, helping the signaller to ensure it is safe for the train to proceed.

Based on an interpreter for a …