Stackless Python is a variant of CPython. It's named stackless because it is implemented such that it does not use the C stack.

Stackless Python is not a Python extension that you can use on top of a preexisting Python installation. It is a complete Python distribution in itself, with (considerable) modifications in the C sources of the original Python implementation.

The essential abstractions are `Tasklets`:trac: and `Channels`:trac:.