In a nutshell, Python doctest has the programmer put an example "interactive session" in a functions docstring. A doctest module then extracts those, tries running the function on the inputs and sees if it matches the output. Best shown by an example:
By the way, python does this by creating a temporary module from the docstring, then evaluating this. Is there a dynamic way in Haskell to evaulate a module? Or will I have to be content starting some sort of "subsession"... Which will make the doctest module less robust & portable. One idea would be just to produce a set of modules in the "core" doctest module. Then there would be a set of lightweight scripts for automating "produce & run" in various environments. But if there is a good "internal" way that I don't know about, I'm all ears. - Shaun