Rust analyzer is a language server for the Rust programming language. I've tried to produce a patch for the latest version, and it has probably hundreds of dependencies that need to be updated.
In addition to that, rust-analyzer is under heavy development and there is a release every month. Many people will want to use the nightly version too. As long as there is rust and rust-cargo in Guix, then rust-analyzer can be easily compiled and installed from git with "cargo xtask install --server" using the rust-cargo system. I'd suggest that a Guix package for rust-analyzer is not needed, especially due to the excessive time required to update its package definition and all of the vendored dependency crates, and focus should instead be on rust and rust-cargo. With regards, - Paul
