[Haskell-cafe] Short circuiting and the Maybe monad

[Derek Elkins]

On Wed, 2008-05-14 at 12:42 -0700, Dan Piponi wrote:
> On Wed, May 14, 2008 at 12:03 PM, Andrew Coppin
> <andrewcoppin at btinternet.com> wrote:
> 
> > "It is well-known that trees with substitution form a monad."
> 
> Now that's funny. Compare with the first line of this paper:
> http://citeseer.ist.psu.edu/510658.html

Well, it's well-known.

Further, not only do they form a monad, but they are a free monad.