"First, it's important to take into account that ZeroMQ was intended to be a piece of infrastructure with continuous uptime. If should never fail and never exhibit undefined behavior."

There is one language/platform[1] I'm aware of designed for this type of system, and which achieves it beyond all others: erlang.

If Uptime is important, how do you handle it when you want to update your software under C++ or C? You have to bring the service down. Erlang supports updating software while its still running.

If exception handling is important (to prevent crashes) how do you handle it when there is a bug? Erlang has supervisors that not only help you manage exceptions but keeps the service going when an unhanded exception causes things to crash.

More importantly, intrinsic to the nature of the way you write erlang code, you eliminate a great deal of the possible errors. In C code you have to check to make sure things are in the right state while running your code. In erlang, your code doesn't run (the function isn't called) if the state isn't right to handle it. It flips this problem eliminating many classes of errors. Further there is OTP support for many types of processing (like state machines) that makes writing these types of solutions much easier.

Erlang is great for making sure no undefined behavior happens. Erlang is also great (as I understand it, this I haven't gotten into) for creating unit tests that can fully exercise the code across all possibilities.

Where does erlang suck? I don't think it sucks anywhere because it has solutions for all of its own problems. For instance, single node performance of an erlang program (which runs in the BEAM VM) is going to be lower than single node performance of a C program... but in erlang you can increase capacity nearly linearly simply by adding more nodes... while this is nearly impossible with almost all C/C++ programs without spending a lot of time working on it.

But where erlang is weak is that single node performance which might be really important[2], and if it is, you can then write your performance critical bits in C.

Thus the things that do the real work can be fast and in C but the things that keep the system going and distributed (where performance of this kind is much less critical, but performance of the operational kind is paramount) can be written in erlang.

So, I think the second mistake he made, and is still making, is thinking that the project has to be written in a single language.

If you use the best language for the job, then sometimes that should mean using two languages right?

Erlang is not a hipster language. No hipsters use erlang. It is 25 years old and boring and %99.9999999 uptime. Its ugly. Its not hot and fresh and new. But it is the right language for the job, when you've got a system that need to run across cores or nodes, or have very high uptime.

And really, it doesn't take but a couple weeks of learning. Then the syntax will be gorgeous and you'll be a better programmer for it.

[1] I say "I'm aware of" for a reason. There may be others as well suited when this is the primary goal, possibly even better suited. I don't know all languages. But I do have a pretty good survey started in the days when new languages were as common as YC batches and much more experimental than they are now. My point isn't to bash other languages but to promote one that isn't understood correctly by many people.

[2] I think this is the case a lot less often than people think. People benchmark things on a single node even when they know they are going to build a cluster of machines to run them, and then pick them based on this. Redis is really fast. Is redis distributed? Riak has a fully distributed in memory database (which means 10 32GB nodes means you can store 320GB in RAM if you want, rather than have 10 nodes all storing the same data in a cache, and thus much less data cached for the same number of machine with something like Redis.