>> Heh, man... I thought "it inserts user-defined code between each pair of
>> statements" would a pretty simple idea. I guess not... ;-)
>
> I should have said that I am none the wiser. I still do not know what a
> monad is.

If you have a set of things which can be "added" and "subtracted" in a 
certain technical sense, this is called a monoid.

(The technical rules say things like "if you add X and Y, and then 
subtract Y, the result has to be X". Stuff like that.)



A monad is a little more complicated, but essentially, if you have

- A "box" type of some sort.

- A "return" function that takes a value and sticks it in a box.

- A "bind" function that takes a box and a function that returns a box, 
and calls that function with the thing(s) in the input box.

then that's a monad.

(Once again, there's a bunch of technical rules that make this 
mathematically rigorous. Technically the functions have to obey certain 
rules - the "monad laws" - such as "bind x id == x". But usually any 
sane way of implementing the two functions about will satisfy the 
requirements.)

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