That's great, unless the imperative programmer happens to be one of the 90% of programmers that isn't particularly familiar with group theory... On 8/1/07, Greg Meredith wrote:

Haskellians,

Though the actual metaphor in the monads-via-loops doesn't seem to fly with this audience, i like the spirit of the communication and the implicit challenge: find a pithy slogan that -- for a particular audience, like imperative programmers -- serves to uncover the essence of the notion. i can't really address that audience as my first real exposure to programming was scheme and i moved into concurrency and reflection after that and only ever used imperative languages as means to an end. That said, i think i found another metaphor that summarizes the notion for me. In the same way that the group axioms organize notions of symmetry, including addition, multiplication, reflections, translations, rotations, ... the monad(ic axioms) organize(s) notions of snapshot (return) and update (bind), including state, i/o, control, .... In short

group : symmetry :: monad : update

Best wishes,

--greg

-- L.G. Meredith Managing Partner Biosimilarity LLC 505 N 72nd St Seattle, WA 98103

+1 206.650.3740

http://biosimilarity.blogspot.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Haskellians, But, along these lines i have been wondering for a while... the monad laws present an alternative categorification of monoid. At least it's alternative to monoidoid. In the spirit of this thought, does anyone know of an expansion of the monad axioms to include an inverse action? Here, i am following an analogy monoidoid : monad :: groupoid : ??? i did a search of the literature, but was probably using the wrong terminology to try to find references. i would be very grateful for anyone who might point me in the right direction. My intuition tells me this could be quite generally useful to computing in situation where boxing and updating have natural (or yet to be discovered) candidates for undo operations. i'm given to understand reversible computing might be a good thing to be thinking about if QC ever gets real... ;-) Best wishes, --greg On 8/1/07, Greg Meredith wrote:

Haskellians,

Though the actual metaphor in the monads-via-loops doesn't seem to fly with this audience, i like the spirit of the communication and the implicit challenge: find a pithy slogan that -- for a particular audience, like imperative programmers -- serves to uncover the essence of the notion. i can't really address that audience as my first real exposure to programming was scheme and i moved into concurrency and reflection after that and only ever used imperative languages as means to an end. That said, i think i found another metaphor that summarizes the notion for me. In the same way that the group axioms organize notions of symmetry, including addition, multiplication, reflections, translations, rotations, ... the monad(ic axioms) organize(s) notions of snapshot (return) and update (bind), including state, i/o, control, .... In short

group : symmetry :: monad : update

Best wishes,

--greg

-- L.G. Meredith Managing Partner Biosimilarity LLC 505 N 72nd St Seattle, WA 98103

+1 206.650.3740

http://biosimilarity.blogspot.com

-- L.G. Meredith Managing Partner Biosimilarity LLC 505 N 72nd St Seattle, WA 98103 +1 206.650.3740 http://biosimilarity.blogspot.com

On 01/08/07, Greg Meredith wrote:

Haskellians,

Though the actual metaphor in the monads-via-loops doesn't seem to fly with this audience, i like the spirit of the communication and the implicit challenge: find a pithy slogan that -- for a particular audience, like imperative programmers -- serves to uncover the essence of the notion. i can't really address that audience as my first real exposure to programming was scheme and i moved into concurrency and reflection after that and only ever used imperative languages as means to an end. That said, i think i found another metaphor that summarizes the notion for me. In the same way that the group axioms organize notions of symmetry, including addition, multiplication, reflections, translations, rotations, ... the monad(ic axioms) organize(s) notions of snapshot (return) and update (bind), including state, i/o, control, .... In short

group : symmetry :: monad : update

Best wishes,

--greg

Hello, I just wrote http://www.haskell.org/haskellwiki/Monads_as_computation after starting to reply to this thread and then getting sidetracked into writing a monad tutorial based on the approach I've been taking in the ad-hoc tutorials I've been giving on #haskell lately. :) It might be worth sifting through in order to determine an anthem for monads. Something along the lines of: "monads are just a specific kind of {embedded domain specific language, combinator library}" would work, provided that the person you're talking to knows what one of those is. :) I've found it very effective to explain those in general and then explain what a monad is in terms of them. I'm not certain that the article is completely finished. I'm a bit tired at the moment, and will probably return to polish the treatment some more when I'm more awake, but I think it's finished enough to usefully get the main ideas across. - Cale