Roslyn API basically lets you plug in to the C# compiler or use parts of it so that you can get the same view of the abstract syntax tree, typechecking, flow an

Roslyn API basically lets you plug in to the C# compiler or use parts of it so that you can get the same view of the abstract syntax tree, typechecking, flow analysis, etc. that the compiler does. So it's a way to work with C# code at that level rather than just via textual manipulation. I'm less familiar with other languages but I think many have compilers with analogous capabilities, I know Haskell has the GHC API and I think the LLVM-based Clang (C++) and Rust compilers let you do similar things