Re: [Haskell-cafe] Track Exceptions

Well, Ghc 7.10 is planned to have Stack Traces, which should be exposed as part of the Exceptions data model once that gets added, I believe that will help quite a bit! -Carter On Thu, Mar 13, 2014 at 1:09 PM, Ruud Koot wrote:

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Simply instantiating b with b `Throws` e gives

map :: (a -> b `Throws` e) -> [a] -> [b `Throws` e]

Which is actually a more useful type than the one you proposed, because it shows that map itself doesn't throw exceptions (so that e.g. computing length is safe).

Assuming "Throws e" is a monad, you could use mapM instead of map to get

On Thu, Mar 13, 2014 at 5:54 PM, Roman Cheplyaka wrote: the

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behavior you want.

In fact, Throws will probably need to be an indexed monad.

Roman

Yes, lazyness complicates things even further. You can pass a function to map that produces an "exception value" of type b. These exceptions would be attached to the elements inside the list [b] as you suggest. But there might also be exceptional values hidden inside the spine of the second argument of type [a]. These would need to end up in the spine of the resulting list of type [b].

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