PyCharm provides initial Cython support out of the box. PyCharm recognizes .pyx, .pxd, and .pxi files, and allows you to edit them. You can also compile these files into .so files using the Cython package.
Cython support
Cython files are marked with the icon.
Cython support includes:
Coding assistance:
Error and syntax highlighting.
Code completion for keywords, fields of structs, and attributes of extension types.
Press Ctrl+Alt+S to open the project settings and navigate to Project: <project name> | Python Interpreter.
Click on the package toolbar, then type Cython in the search field of the Available Packages dialog, and click Install Package. Close the window upon successful installation and click OK in the interpreter settings.
Now create a .pyx file. Select File | New from the main menu, then select File. Type the filename, for example, example.pyx and save the changes. The file opens in the editor.
You can copy and paste the following code:
def function (a: int, b: int) -> str:
return str(a + b)
function(2, 4)
Alternatively, you can type code to see how PyCharm assists you with code completion and type checking:
Now create the setup.py file. Select Tools | Create setup.py from the main menu. PyCharm creates a template setup.py file and opens it in the editor. You can copy and paste the following setup options:
To compile the example.pyx file, select Tools | Run setup.py Task command from the main menu. In the Enter setup.py task name type build and select the build_ext task. See Create and run setup.py for more details. In the Run Setup Task build_ext dialog, add the --inplace command-line agrument Once the build task successfully completes, the .so file is created.
At this point, you can use the compiled .so file to import function:
icon.
on the package toolbar, then type 
