[Haskell-cafe] Refactoring recklessly

[Neil Mitchell]

Hi

> I'd like to be able to reorganize my code and then verify that I didn't
> change any functionality.  That is, the old and new code have precisely the
> same meaning.
>
> Also, I'd like to be able to change a function and verify that efficiency
> was the only thing affected.
>
> Are either of these possible in Haskell or any language?

They are possible in any language, just in some they might have a lot
of work to do the proofs. In Haskell they are pretty easy:

http://haskell.org/haskellwiki/Haskell_Equational_Reasoning_Assistant

(More one function at a time, not publically available, as far as I can tell)

http://www.cs.kent.ac.uk/projects/refactor-fp/hare.html

(Global refactorings, a nice tool)

Thanks

Neil