Kris, Sorry for the confusion, I wasn't directly addressing your post. I was trying to correct what I perceived as a misconception in the last paragraph of Andrew's message, beginning with "Given that…".
- Joel On Saturday, September 15, 2012 at 10:24 AM, Kristopher Micinski wrote: > On Fri, Sep 14, 2012 at 10:08 PM, Joel Burget <joelbur...@gmail.com > (mailto:joelbur...@gmail.com)> wrote: > > [snip] > > > > Also, Maybe and Either are not "implemented as monads". They are defined > > using `data` like you suggest: > > > > data Maybe a = Nothing | Just a > > data Either a b = Left a | Right b > > > > > That's not my point, or my objection. My objection is to people who > present monads showing examples that begin with Maybe or Either, or > these 'trivial monads,' types onto which you can strip monadic > behavior fairly simply. I'm not saying they're bad as monads, or > useless, but I think the step from Maybe as a datatype to using it as > a monad is great enough that explaining monads by way of introducing > them with Maybe as an example is sort of confusing because it > trivializes what's actually going on. > > I'm honestly not sure what you mean by Maybe or Either being > "implemented as monads," versus others. Monad is just a type class, > there's always an underlying type. Perhaps you mean that people > actually *care* about things in Maybe outside of it being used as a > monad, versus other things where you don't touch the underlying type. > > This isn't intended to start an argument, however, and I'd prefer not > to argue over methodology, I just wanted to throw out there that if > you say "monads, think about maybe, and add some stuff, then that's it > is, what's all the fuss about!?" I think the hard part for people > understanding monads isn't the definition of monads, but rather that > you are forced to really tackle higher order behavior in a very direct > way. (For example, say you're new to Haskell, you probably don't know > about CPS, and you read about Cont in a monad tutorial. Is it the > monad that makes it hard? No, it's probably the concept of CPS.) > > kris
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