Moving into more opinionated territory, the tools, languages and methodologies used in software development are more artifacts of religious providence than objective reality. Source code is like written prose. Everyone has an opinion of what is good — and what is being communicated is, at times, less important than how it is communicated.
We must commit the sin of choosing a side accepting that it will be wrong in at least one person’s eyes. However, there is at least a large corpus of justification behind our choice.
The protocols making Cardano possible are being implemented in Haskell. The user interface has been encapsulated in a fork of Electron that we are calling Daedalus. We have chosen to use the web architectural model where possible, and for our database, we opted for a key-value paradigm using RocksDB.
From a component level, this abstraction means that maintenance is far simpler, better technology can be substituted later with little effort, and that our stack is partly tied to the development efforts of Github and Facebook.
Choosing Haskell for protocol development was the most difficult choice. Even in the functional world, there are ample choices. On the more flexible and impure side, there are languages like Clojure, Scala and F#, which benefit from the enormous libraries of Java and the .Net ecosystems while preserving some of the best aspects of functional programming.
There are more academically oriented languages such as Agda and Idris that have a close connection to techniques that would allow for strong verification of correctness. Yet they lack reasonable libraries and have a subpar development experience.
For Cardano, the choice came down to Ocaml and Haskell. Ocaml is a wonderful language with a great community, good tooling, reasonable development experience and a great legacy in the formal verification space through Coq. So why did we choose Haskell?