I'm not sure if the other answers were good enough.
NIF is native interop. There's a bunch of provided functions for interfacing with Erlang terms and other things like that. But, it's native interop, so you can also do whatever crazy stuff you want, even if it's a bad idea.
The BEAM VM cannot and does not protect you from bad NIFs; but if you follow the guidelines and are careful not to crash, you can have a good time. Often, the scope of the native work ends up so small, it's easyish to keep it safe. For larger scope, it's more common to use a Port or a C-node; a Port is just what Erlang calls running your other code in separate OS process communicating with stdin/stdout, and a C-node is your other code running separately, possibly on another machine, connected via network sockets, acting like a dist node. For this application though, it makes more sense to use a NIF to avoid copying the data to and from a separate OS process.
I haven't used Rustler, but my understanding is it's mostly just a framework of sorts for writing NIFs in Rust. Maybe making it easier to use Erlang terms, and setting up the compile settings etc.
NIF is native interop. There's a bunch of provided functions for interfacing with Erlang terms and other things like that. But, it's native interop, so you can also do whatever crazy stuff you want, even if it's a bad idea.
The BEAM VM cannot and does not protect you from bad NIFs; but if you follow the guidelines and are careful not to crash, you can have a good time. Often, the scope of the native work ends up so small, it's easyish to keep it safe. For larger scope, it's more common to use a Port or a C-node; a Port is just what Erlang calls running your other code in separate OS process communicating with stdin/stdout, and a C-node is your other code running separately, possibly on another machine, connected via network sockets, acting like a dist node. For this application though, it makes more sense to use a NIF to avoid copying the data to and from a separate OS process.
I haven't used Rustler, but my understanding is it's mostly just a framework of sorts for writing NIFs in Rust. Maybe making it easier to use Erlang terms, and setting up the compile settings etc.