I don't know if anyone remembers expression templates of C++ nowadays. Once upon a time I had written a library of expression templates primitives to chain stre

I don't know if anyone remembers expression templates of C++ nowadays. Once upon a time I had written a library of expression templates primitives to chain streams of computations and maps so that the sub-streams do not need to be fully realized in memory - essentially the old idea of Unix pipelines. Writing it was a lot of fun. Debugging compiler errors were a lot less fun because the template language of C++ has no static typing, so errors would be triggered very deep in the expression tree. The expression tree got processed and inlined at compile time so there was no to minimal overhead at runtime. I was very impressed with GCC's inlining and vectorization. Especially the messages that explained why it could not vectorize.