Analyzing Functional Reactive Programming in ELM and JavaScript

Functional Reactive Programming (FRP) languages allow to build interactive and highly responsive GUIs by using the features of pure Functional Programming (FP). Most of the currently famous FRP frameworks "imitate" the features of pure FP languages, whereas the pure FRP languages are not being widely used in the industry. Motivated by the under-appreciated promise of pure FP languages, we will investigate the reasons of their unpopularity by looking at their history and disadvantages.;In this thesis we are going to focus on two FRP languages: ELM and React.js. ELM is a pure FRP language which compiles into JavaScript. It eliminates a lot of issues related to the efficiency and expressiveness that previous FRP formulations had. Furthermore, we are also going to talk about one of the most famous FRP frameworks called React.js. React is a library for JavaScript which is prominent for its simplicity and ease of use with existing projects.;Pure FRP languages provide a better performance since they manipulate DOM more efficiently. To demonstrate the full power of pure FRP, we will compare the performance and code sizes of the modified TodoMVC applications written in both ELM and React. We have modified the TodoMVC applications to support an additional feature, which will enable the user to mark tasks with specific importance levels.