I think Rust scratched a deep itch by targeting people who are unhappy with C++ and definitely started off targeting a bigger, less competitive market than Julia.
Julia has a harder marketing job than Rust. Julia needs to convince people who use $slow_dynamic_language and $fast_static_language together that they'd be better served by just using Julia for both jobs.
Even more importantly though, julia needs to convince people that it's premise is even possible. People have deep seated biases that make them unaware that it's even possible for a dynamic, garbage collected language to be fast.
Rust on the other hand 'just' has to convince people that it's a better ~1:1 replacement for C++. Most people who have written C++ deeply believe that a better language is possible and yearn for that language.
Python, R and Matlab users typically don't believe that it's possible for a language to do what julia does.
Furthermore, Julia did initially spend a lot of marketing effort on the scientific community, which is somewhat small, and is more composed of people who just see their language as a tool that only needs to be 'good enough', so they're less likely to want to switch than say systems programmers who spend all day faced with C++'s inadequacies.
I think an even bigger aspect of this is that C++ users are technical people who make technical decisions. If Rust is a better tool for them, they will switch. For a lot of scientific programmers, or even just a lot of general Python users, they don't necessarily choose Python because they know 20 languages and think Python is the best tool for the job. A lot of people use Python because... they use Python and it's what they were taught. That's a much harder audience to go to and say "would you change to this technically better language?". Most just say "I'm not really a programmer, I'm a researcher/scientist/etc. so I shouldn't spend time learning more programming", and that makes it fairly difficult.
Speaking from personal experience, I would add that some people use Python, not only because that's what they already know, but also because... everyone else in their field is using Python and its ecosystem. New advances in their field occur largely within the confines of that ecosystem. It's hard to leave the pack behind.
Large ecosystems have significant network effects that act as barriers to new entrants.
Yeah definitely. That's what I was trying to get at in the last paragraph, and you might be right that it's an even bigger aspect than the other things I mentioned.
Julia has a harder marketing job than Rust. Julia needs to convince people who use $slow_dynamic_language and $fast_static_language together that they'd be better served by just using Julia for both jobs.
Even more importantly though, julia needs to convince people that it's premise is even possible. People have deep seated biases that make them unaware that it's even possible for a dynamic, garbage collected language to be fast.
Rust on the other hand 'just' has to convince people that it's a better ~1:1 replacement for C++. Most people who have written C++ deeply believe that a better language is possible and yearn for that language.
Python, R and Matlab users typically don't believe that it's possible for a language to do what julia does.
Furthermore, Julia did initially spend a lot of marketing effort on the scientific community, which is somewhat small, and is more composed of people who just see their language as a tool that only needs to be 'good enough', so they're less likely to want to switch than say systems programmers who spend all day faced with C++'s inadequacies.