On Fri, 8 May 2020, Niklas Hambüchen wrote:

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What are "unintended exceptions"? What is an example of an "unintended exception"?

A recent example from my production server:

hPutBuf: resource vanished (Broken pipe)

Ok, I lookup the Haddock comment of hPutBuf and it says: "This operation may fail with: * ResourceVanished if the handle is a pipe or socket, and the reading end is closed." That is, ResourceVanished is part of the public interface and in no way unexpected (or what "unintended" may be). I would prefer to make this explicit in the type of hPutBuf: hPutBuf :: (ResourceVanishedException e) => Handle -> Ptr a -> Int -> ExceptT e IO () Now, what do you intend to do with the call-stack? Isn't it something you can attach to the e value?