Re: Proposal: Applicative => Monad: Call for consensus

Gábor Lehel schrieb:

On Tue, Jan 4, 2011 at 1:25 PM, Ian Lynagh wrote:

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On Mon, Jan 03, 2011 at 11:30:44PM +0100, Bas van Dijk wrote:

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2) Make 'join' a method of Monad.

Why?

Of course I'm only a sample size of one, but I find join a lot easier to think about and implement than (>>=). Even trying to look at it objectively and factor out my own potential idiosyncracies, it's obvious that it only has one argument to (>>=)'s two, and the type signature looks a lot more straightforward any way I slice it. I was very glad to see this proposal to make it possible to define a Monad using return (pure), fmap, and join, rather than return and (>>=).

Mathematically I like 'join' more than '>>=', but for RMonads like StorableVector you will in general be able to define a '>>=' but not 'join'. Of course, you can ignore this reason, because Monad is not RMonad, but for reasons of consistency it might count.