Existing functional languages had their own issues:
1. Haskell: had to deal with cabal hell
2. Scala: Java toolchain, VM startup time, dependencies requiring differing Scala versions.
3. F#: .NET was considered too Microsofty to be taken seriously for cross platform apps.
4. OCaml: "That's that weird thing used by science people, right?" - Even though Rust took a decent amount of ideas from it, it got validated by its early users like Mozilla and Cloudflare, so people felt safer trying it.
5. Lisp: I don't think I need to retell the arguments around Lisp. Also a lot of the things Rust touts as FP-inspired benefits around type systems really aren't built into lisp, since it's dynamically typed, these come more from the Haskell/Scala school.
1. Haskell: had to deal with cabal hell
2. Scala: Java toolchain, VM startup time, dependencies requiring differing Scala versions.
3. F#: .NET was considered too Microsofty to be taken seriously for cross platform apps.
4. OCaml: "That's that weird thing used by science people, right?" - Even though Rust took a decent amount of ideas from it, it got validated by its early users like Mozilla and Cloudflare, so people felt safer trying it.
5. Lisp: I don't think I need to retell the arguments around Lisp. Also a lot of the things Rust touts as FP-inspired benefits around type systems really aren't built into lisp, since it's dynamically typed, these come more from the Haskell/Scala school.