with C++ - it was very complex, hard to understand, missing concurrency support, didn’t scale, and had really long build times. A common pattern at Google was that someone would have an issue with C++. They’d send out an email soliciting advice; everyone would reply with a different answer.
a higher-order function (also functional form, functional or functor) is a function that does at least one of the following: takes one or more functions as an input.