I'd also like to hear what others do to learn languages. I like to write a little RPN calculator. The program's interface might vary depending on the language:

I'd also like to hear what others do to learn languages. I like to write a little RPN calculator. The program's interface might vary depending on the language: to learn browser JS, you might do a DOM-based UI; for Rust it might be a CLI; for Go or Erlang maybe a line-oriented network service. Depending on the interface, this tends to exercise language and runtime features like: string handling and parsing, event handling, conditionals / pattern matching, etc. "Calculator" is also a big enough problem space that you can come back to it to try out more interesting language features (e.g. using Rust enums to model your calculator's operations).