C and C-style languages like C++, Java, and C# tend to have method types written like this:
Other typed languages and programming papers use a notation more like this:
I found it took a bit of getting used to, but I now much prefer to read and write this style. I think it is worth becoming familiar with, as it is used in quite a few languages1 and in all the programming papers I’ve seen. So here’s a quick guide on how to read this style of type annotation.