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JUSPAY Technologies Pvt Ltd


10x Faster Mobile App Dev with PureScript

Submitted Sep 8, 2017

At Juspay, after spending a few years writing various payments applications, we found
ourselves looking for a better way. We wanted to allow newcomer developers, designers and
project managers to be able to jump in and start creating solutions to their problems, without
jumping through the hoops created by the language and tools.

As a JavaScript house, we explored a number of options and chose PureScript as our core
language. It paired the conciseness of Haskell with the ubiquity of the JavaScript interpreter,
allowing us to make a staged transition. We modeled the UI components and business flows as
simple, pure functions that are reusable across apps. The frontend and backend were naturally
unified, and could be represented as a continuation of flow between the client and server.

In the last several months, we have made major strides towards allowing everyone in our
company to be able to examine and write code for the apps we are building. We have trained
around 100 interns on Haskell and PureScript to work on our platform in production. We have
been able to deploy this framework into production in mission critical payment and banking

In this talk, we will talk a bit about the framework we have built, and then dive into our rationale
for choosing PureScript as our language, our experiences in transitioning from JavaScript to
PureScript, and what we have learned along the way.


  1. Speaker Intro
  2. Problem: commercial apps take millions of $$ to maintain
  3. Why are apps hard?
  4. How does Presto solve this problem?
  5. How1: Presto’s UX DSL
  6. How2: Business Flows as Composable Goal Tree & Code Walkthrough
  7. How3: The choice of a Pure FP language
  8. How4: Architecture unification to just 3 building blocks
  9. Why was PureScript chosen? Why use CPS architecture?
  10. How does this add up to 10x?
  11. Example Apps in production
  12. Next Steps



Speaker bio

Vimal Kumar, CEO Juspay
We have built and maintained multiple large scale payments apps (eg. BHIM), with a young team. Our learnings over the last few years helped us build Presto.




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