On 8/1/07, Andrew Wagner
For me, I think the key to monads is to really understand 2 things about them: ... 2.) Monads are about sequencing
Now I disagree on 2. Monads are no more about sequencing than binary operators are about sequencing. Sure, if you want to, you can define an operator like (*) to be non-commutative, so that a*b is different to b*a, but that doesn't really get to the essence of what a binary operator is. And in everyday usage we use (*) to mean ordinary commutative multiplication where there is no sense of sequencing. The same holds for monads. If you want to use them for sequencing the option is there, but there are plenty of commutative monads out there, for which the order of operations doesn't matter, and the fact that they are commutative doesn't make them any less monads. So while you can use monads to sequence, I don't think sequencing gets to the essence of what monads are. I suspect I hold a minority view here... :-) -- Dan