Re: Open source
You'd be surprised. First off anything that lives in a niche, tied to a vendor product is almost certainly a closed source language. This is especially the case in the enterprise analytics space. Think of your Matlabs, your SASes, your SQLs, your godforsaken crosses between SQL and procedural. Then you've got your commercial C/C++ variants (hello MSVC!). Let's not even get started on the likes of Apex.
Closed source programming: surprisingly common.
Biting the hand that feeds IT
