[Haskell-cafe] Commutative monads vs Applicative functors

[Janis Voigtlaender]

Ronald Guida wrote:
> From what I have read about applicative functors, they are weaker than
> monads because with a monad, I can use the results of a computation to
> select between alternative future computations and their side effects,
> whereas with an applicative functor, I can only select between the
> results of computations, while the structure of those computations and
> their side effects are fixed in advance.

If you are not already aware of them, you might be interested in the 
following two papers:

http://homepages.inf.ed.ac.uk/wadler/papers/arrows-and-idioms/arrows-and-idioms.pdf

http://homepages.inf.ed.ac.uk/wadler/papers/arrows/arrows.pdf

("idioms" is a synonym for "applicative functors", and both papers also 
discuss the relation to monads.)

Ciao, Janis.

-- 
Dr. Janis Voigtlaender
http://wwwtcs.inf.tu-dresden.de/~voigt/
mailto:voigt at tcs.inf.tu-dresden.de