Hey - maintainer of ReasonReact here. We don't believe in mandating the tools that people use and there are plenty of good reasons to use TS, Flow, PureScript, Rust, etc. Folks on the Messenger Web team in Facebook like Reason as their language of choice. Reason is used heavily on Messaging code in the old facebook.com and in this rebuilt version.
The rebuilding of facebook.com was done quickly and involves almost every web team at Facebook. Almost all of these folks are familiar with Flow and only some are familiar with Reason. Asking every engineer at FB to learn Reason at the same time in addition to the already massive number of new things would have been adding unnecessary risk to this already incredibly risky project.
The rebuilding of facebook.com was done quickly and involves almost every web team at Facebook. Almost all of these folks are familiar with Flow and only some are familiar with Reason. Asking every engineer at FB to learn Reason at the same time in addition to the already massive number of new things would have been adding unnecessary risk to this already incredibly risky project.