TDD in a REPL

REPLs (Read-Eval-Print-Loops) are often billed as a great place to experiment and learn a language or a framework. They provide a very tight feedback loop. However, it can be difficult or time-consuming to extract the knowledge gained from a REPL and include it in your source code. I’ve hit the up arrow many times in Ruby’s pry, trying to find the specific input I wanted to copy. And don’t get me started on dealing with multi-line input. Thankfully, the developers behind F# came up with a clever way of dealing with this problem. Read more on TDD in a REPL…