[Haskell-cafe] Commutative monads vs Applicative functors

Ronald Guida oddron at gmail.com
Wed May 14 14:06:13 EDT 2008

David Menendez wrote:
> To summarize: some applicative functors are commutative, some
> applicative functors are monads, and the ones that are both are
> commutative monads.

OK, so commutativity is orthogonal to "idiom vs monad".  Commutativity
depends on whether or not the order of side effects is important.
Being a monad or just an idiom depends on whether or not "join" is
supported.  Examples can be constructed for all 4 possibilities of
{idiom,  monad} (x) {non-commutative, commutative}.

Thank you all for clearing this up for me.

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