On Mon, Aug 19, 2013 at 05:15:39PM -0400, jabolopes@google.com wrote:

But I would like to see more code move away from exceptions and into types like "Maybe" or "Either" or other types defined for the particular situation (as some people were suggesting in the beginning of the thread). And the reason for this it is because when you program against types you have to make a decision whether to handle the error or let it bleed through: you can't ignore the choice because you can't ignore the type. On the other hand, with exceptions, you can easily forget to handle the exception if you're not looking at the documentation at the time when you write the code.

This is /exactly/ the reason to avoid exceptions where possible. Tom

jabolopes@google.com :

I would like to see more code move away from exceptions and into types like "Maybe" or "Either" or other types defined for the particular situation (as some people were suggesting in the beginning of the thread). And the reason for this it is because when you program against types you have to make a decision whether to handle the error or let it bleed through: you can't ignore the choice because you can't ignore the type. On the other hand, with exceptions, you can easily forget to handle the exception if you're not looking at the documentation at the time when you write the code.

Tom Ellis:

This is/exactly/ the reason to avoid exceptions where possible.

I disagree. Types which neutralize some particular conditions (whether you call them exceptional or not is conventional) and propagate "Nothing" etc. is not a panacea. Some exceptions, e.g. in the traversal of deep structures may be and ARE used as escaping continuations. Calling all that "not the right thing to do", or issuing other normative statements is, how would I express it... , is not the right thing to do. Now you can add here some dozen smileys... More seriously, some people like exquisite continuations and will use them. Instead of fighting against exceptions it might be more fruitful to make them more robust, powerful, parametrable and sexy. Jerzy Karczmarczuk

Le 20/08/2013 00:19, jabolopes@google.com a écrit :

If I understand correctly, by "escaping continuations" you mean that you can easily transfer control between the point where the exception is raised and the exception handler.

If this is what you mean, you can achieve the same effect with monadic code by chaining monads together

Yes. José, this is mainly the question of efficiency. You don't need to establish contact between the distant stack frames, and you may propagate failures if this happens seldom. But if the escaping continuation is a frequent case, it might be more economic to "jump". This is as simple as that. Jerzy Karczmarczuk