> If you know Python, it'll be easier to learn Rust than having to learn Rust from zero.

> Learning one of anything makes learning the next one easier

Agreed, but I put easy, not easier. I suspect we really agree on all points.

If you know C#, it's easy to learn Java, as most the concepts are shared, and even the syntax is very similar. When someone says If you learn to program in one language, it's easy to learn another, it betrays that they don't understand that some languages are similar, but some are very different and have unavoidable learning curves.

C++ is a good example. Learning C++ is not easy, no matter what your background knowledge of other concepts and languages. It's a huge language, in which nothing is simple. Even the build model is a minefield. Having a solid understanding of imperative programming and OOP (from knowing Java, say) is certainly an important head-start. I wouldn't recommend C++ as someone's first programming language. There's still an enormous amount to learn about C++ specifically, no matter your background knowledge.

It’s also worth noting that projects are rarely contained within the bounds of a programming language.

If you’re building a web app, what’re language you use will still come down to HTML/css. You’ll also probably be using SQL, which is also unlikely to change.

But there’s the other side to that. If you’re graphics programming, OpenGL provides the same features regardless of language. The OS APIs are broadly the same - the steps to set up a TCP listener don’t change with the language.

The APIs for all these may be subtlety different between languages, but not significantly. It’s a case of translation rather than relearning, and although I can’t speak for anyone else I find that translation quite painless.

Learning Python before Haskell also made learning Haskell significantly harder for me, because I kept trying to write Python in Haskell

Sure, but it will still be a while before you aren't just writing Python in Rust.

It’s still easier than if you had never previously written an if statement. If there weren’t a lot of differences between languages then we wouldn’t have so many languages, but that doesn’t mean that there are not a lot of concepts that are used widely across many languages.

However the more languages you know and the more they're spread across different paradigms the shallower the learning curve will be for any language one wants to pick up.

Be fair to the original comment, which referenced people saying something about learning a language, and it making learning any others easy, not about learning many languages, and it making learning any others easier.

Writing Python in Rust unlike say writing C++ in Rust, might actually be a desirable thing. Put it this way, It will be a while before you are writing Rust like Python.