Go is not sequential, but concurrent. It has built-in primitives for handling concurrency, witness the `go` keyword. It also has special syntax for doing selective receive over channels, which in turn means that the concurrency of that language is definitely not "bolted on" in the sense I meant.

Perhaps you are confusing my definition of "sequential" with yours. I tend to use "sequential" as the opposite of "concurrent" like I have another, orthogonal, axis for "serial"/"parallel". So you can be serial/concurrent (Node.js is close to this. So is a 4.4BSD OS without any SMP support). And you can be sequential/parallel (GPUs is my preferred example).