CPython is written in C, and has an extensive API, also in C. A good number of CPython's stdlib is implemented in C. It's fairly easily to write an extension li

CPython is written in C, and has an extensive API, also in C. A good number of CPython's stdlib is implemented in C. It's fairly easily to write an extension lib in C or C++ or Rust, even, and have python dynamically load the library. Shared libs have to be linked differently than they normally are as ld.so needs to be able to locate and load any dependencies. Libs are typically referred to as 'dlo's instead of 'so's to make the distinction.