[Haskell-cafe] is proof by testing possible?

Dan Piponi dpiponi at gmail.com
Mon Oct 12 14:09:56 EDT 2009


> On Mon, Oct 12, 2009 at 11:03 AM, Joe Fredette <jfredett at gmail.com> wrote:
> I completely forgot about free theorems! Do you have some links to resources
> -- I tried learning about them a while
> ago, but couldn't get a grasp on them... Thanks.

There is Wadler's paper but I do find it tricky:

You can play with the generator here:
The results can look unreadable at first, but I find that if I copy
them onto paper and do all of the remaining substitutions manually
(like I had to do with (a,b) -> (b,a)) you end up with something
readable. If you keep doing this you'll get a good intuition for what
the free theorem for a type will look like.

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