I mean, write a compiler for a reasonable subset of a language you're learning. You can use the language itself to do so, yet most languages are not necessarily

I mean, write a compiler for a reasonable subset of a language you're learning. You can use the language itself to do so, yet most languages are not necessarily designed for writing compilers, so it's ok to use something else instead. This way you'll quickly understand the semantics of the language and will get an early exposure to its dark corners.