Go

Go was designed at Google by people who were tired of large C++ codebases, and every decision in it follows from that. The language is deliberately small — no inheritance, no generics for its first decade, one way to format code and a tool that enforces it. Experienced programmers often find this insulting for a week and then quietly stop missing the features.

The payoff is that Go is unusually easy to read. A codebase written by strangers three years ago is comprehensible, which matters more on a long project than expressiveness does. It also compiles to a single static binary, which makes deployment almost boring — a genuine feature.

The part worth real attention is concurrency. Goroutines and channels are Go's headline idea, and they make concurrent code approachable in a way threads never did. They are also the part people misuse first, which is why concurrency gets its own module here with four teachers in it, including Rob Pike's original talk on the patterns the language was designed around.

About eight hours on the required path. The optional lessons — second and third full courses, conference talks, and four different ways of building an HTTP API — take the whole pool past thirty. Go is a good second or third language and a reasonable first backend one: the standard library alone will get you a working HTTP server without touching a framework.