See Reflex FRP in action with tinker-friendly code samples you can run yourself.
These examples are running at https://examples.reflex-frp.org.
To run the examples locally, install Obelisk, go into the project directory, and run ob run. This will compile the examples using ghc and run them locally on http://localhost:8000/. You can also do modifications to the examples while the ob run command is running, it will recompile them automatically when the file is saved, and reload the page where it's running.