[Haskell-cafe] Error monads (was: Call for comments: neither package)

[Roman Cheplyaka]

* Stephen Tetley <stephen.tetley at gmail.com> [2010-06-29 12:02:45+0100]
> The "Applicative Programming with Effects Paper" has the "monodial
> accumulating" applicative instance on a sum type Conor McBride and
> Ross Paterson call Except:
> 
> data Except err a = OK a | Failed err
> 
> The names are nice and to the point, but they would equally describes
> the other exception model (monadic - exit on first fail) and having
> both might be particularly confusing to newcomers: two error types -
> one with an obvious name, one with an unfamiliar one, the unfamiliar
> one might be the one they need most often...

On a slightly related note, in my projects I tend to define my own
Error-like types with descriptive names, often more than one failure
mode and apropriate instances. For an example of this approach, see
http://github.com/feuerbach/loker/blob/master/testingtool.hs#L33

-- 
Roman I. Cheplyaka :: http://ro-che.info/
"Don't let school get in the way of your education." - Mark Twain