Some projects has more value to be written in Rust:

• Rust's safety allow to use complex patterns more safely
• Concurrent or multi-threaded systems
• Security-critical components

There are three approaches for ar Rust migration:

• Full Rewrite
  • the codebase is relatively small and the scope is tractable
  • there is an exhaustive blackbpx test suite that validates behavior
  • the API surface is well defined and stable
  • the deployment environment is controlled
• Incremental migration for each module
  • all other use cases
• Incremental migration with vertical features: each feature is built from the ground up to use 100% Rust code. Business value can be measured directly.

The incremental migration has its own challenge: FFI with C and C++. The rule of thumb is to keep the code responsible for the memory allocation do the deallocation.