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

Roman Cheplyaka roma at ro-che.info
Tue Jun 29 10:15:43 EDT 2010

* 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

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

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