REPL Python programming and debugging with IPython
When programming in Python, I spend a large amount of time using IPython and its powerful interactive prompt, not just for some one-off calculations, but for significant chunks of actual programming and debugging. I use it especially for exploratory programming where I’m unsure of the APIs available to me, or what the state of the system will be at a particular point in the code.
Source: REPL Python programming and debugging with IPython, an article by Luke Plant.