We implement the Event Sourcing system using HugSQL and iterative development at the REPL.
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This lesson shows an in-depth example of repl-driven development. We start a new project to parse and analyze an unknown CSV file. By taking small steps at the REPL, we develop a program to parse the CSV. We test each step at the repl before moving on, and interactively expand the program. At the end, we have a program to parse it, and we have tested everything carefully along the way.
In this lesson, I go through throwing, catching, and extracting information from exceptions and errors.
Java provides a library called ExecutorService. It’s a thread pool fed by a queue. You send it tasks (functions) and you get back Futures with your answers.
We build a table. You can “expand” rows to reveal more detail about each of the visible rows.
Now that we’re connected to the database, we build out our data model using `CREATE TABLE` statements. These will run every time the server is started.