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While a strong type system is one way to achieve the goal (and probably the easiest one from a language design perspective) it is not the only way. The origina

by evgen 16y ago

While a strong type system is one way to achieve the goal (and probably the easiest one from a language design perspective) it is not the only way. The original E design did not rely upon typing at all but used cryptographic security at the message-passing layer to accomplish the capability semantics desired. Strong typing made it easy to apply the core ideas to Ocaml, for example, but it could have been accomplished in a language with weaker types but a more rigidly designed message-passing architecture like Erlang with just a few tweaks to the VM and OTP system (e.g. a lot of the tools that make hot code loading and debugging things on-the-fly possible in Erlang leak too much information about the system and would have to be changed.)

jerf 16y ago
Yes, I think I wasn't clear. What I was getting at was more about the mentality of programmers; if you can get stronger types into the mainstream you will also get many of the same concepts that you need to understand capability based systems into the mainstream. They aren't, strictly speaking, the same by any means, but right now the ideas in the area of provability, meaningful types, capabilities, and that whole complex of ideas around reifying not just what code does but what it doesn't do, just aren't popular enough yet. FP is the most likely vehicle to get that complex at least somewhat out into the mainstream. Once you have that, you might as well exploit it in your capability-based systems, even if they aren't strictly speaking related. Capabilities, on the other hand, don't look to me like they can lead the charge, but they could ride it.
- evgen 16y ago
  I definitely agree with this. I also think that capability systems that are based on a good type system are probably going to be easier to code with than ones based on message passing security. The type systems make it easier to define and use the basic capabilities and involve a lot less boilerplate code than what one sees in other variants of capability-semantics.

by evgen 16y ago

jerf 16y ago

Yes, I think I wasn't clear. What I was getting at was more about the mentality of programmers; if you can get stronger types into the mainstream you will also get many of the same concepts that you need to understand capability based systems into the mainstream. They aren't, strictly speaking, the same by any means, but right now the ideas in the area of provability, meaningful types, capabilities, and that whole complex of ideas around reifying not just what code does but what it doesn't do, just aren't popular enough yet. FP is the most likely vehicle to get that complex at least somewhat out into the mainstream. Once you have that, you might as well exploit it in your capability-based systems, even if they aren't strictly speaking related. Capabilities, on the other hand, don't look to me like they can lead the charge, but they could ride it.

evgen 16y ago
I definitely agree with this. I also think that capability systems that are based on a good type system are probably going to be easier to code with than ones based on message passing security. The type systems make it easier to define and use the basic capabilities and involve a lot less boilerplate code than what one sees in other variants of capability-semantics.