Sorry, no offense intended. I think I'm ascribing to you something closer to the mainstream view than my own, so you're a stand in for the world :) Not entirely without reason; you haven't said anything in this thread but at other times you've wanted to define your modules in such a way that they'd continue to work regardless of what surrounding modules contain. I'm not sure how far you've moved away from such ideas, and I don't mean to attack you, so where I imply 'you', please assume 'everyone but me'. :)
My radical approach is: "let the caller hack my library to get it to work." Have you been converted quite that far? :)
Er, sorry, I think I must talk in a decisive way that makes me look offended. I'm so indecisive in general, I have to take what I can get. :)
I don't know what would have offended me, so don't worry about it.
"I think I'm ascribing to you something closer to the mainstream view than my own, so you're a stand in for the world :)"
As someone who has spent this thread denouncing the evils of truth and making things, when I hear you calling me mainstream, it's heartwarming. :)
"Not entirely without reason; you haven't said anything in this thread but at other times you've wanted to define your modules in such a way that they'd continue to work regardless of what surrounding modules contain."
Yes, that's something I still consider an essential feature of a module system. And I think module systems themselves are a matter of course if we have a certain culture around collecting discrete snapshots (research).
But I'm interested in how much we can avoid discrete snapshots in the first place, as well as what different cultural attitudes we could adopt.
"My radical approach is: "let the caller hack my library to get it to work." Have you been converted quite that far? :) "
That depends on what context we're discussing this in.
- In the here and now, I'm taking this day to day. I don't have a strong opinion on how much I should indulge my fondness of making things, what I should make or procure for whom, and how much I should work closely with whom. Nor do I have a strong opinion on what you should do. :-p Or maybe it's more accurate to say that I might have strong opinions if presented with more specific situations.
- For thousands of years down the line, I hope we get to "let the caller communicate with me if they want to, under the ethical and logistical supervision of our local peers." There's rarely a "library" involved, and if there is, it's the one who's saying "me" here.
- In the projects I've been working on and pondering, I already have a (very incomplete) plan to allow Era modules to break each other's encapsulation. The idea is that one module should have special privileges with another module as long as it can prove it already knows that module's implementation code or has that module author's permission. A user must have the implementation code of a module in order to install it in the first place, so they can of course hack on it and break compatibility and find themselves rewriting a whole chain of depenencies to use their customization, but this way they can sometimes just add a new module that takes advantage of having extra insider knowledge about the original.
In fact, now that I think about it, this "extra insider knowledge" access is similar to the extra information you're trying to access from your scenarios concept. Hey, we might be able to design a formal system together. :) Did you ever get around to looking at linear type systems?
EDIT to add: I was encouraged to think about this "extra insider knowledge" plan thanks to a recent LtU thread about "private" and "public" access controls: http://lambda-the-ultimate.org/node/4965. The Era module system has only one top-level definition per module, so a private definition doesn't make sense unless there's some way to break into it. Before that thread, I was already worried about what it would take to allow an author to prove extra things about the other definitions they had already published, but that's where I started thinking about a solution.
"Did you ever get around to looking at linear type systems?"
I was (and still am) waiting for you to teach them to me :p
My recent explorations are hardening my bias for operational/ugly/imperative approaches over declarative/elegant/functional ones. The trouble with being elegant is that the implementation is harder to tinker with without causing subtle issues. Later readers have to understand global properties at a deep level.
Don't get me wrong, there's room for high-level languages in my world-view. They're just harder to communicate the big picture of, and I want to start with simpler problems. High-level languages and type systems are hard crystals, and I'm currently more interested in building squishy cells.
"I'm currently more interested in building squishy cells."
I respect that, but just to get it written down, here's what I've come up with so far:
All lambda expressions must be lambda-lifted so they're at the top level of some module. (I guess this might count as a lambda-free logical framework.)
Every function type (X -> Y) is annotated as (X -> [C] Y) with the implementation code C of that function's source module. A simple export/import of an X-to-Y function will actually bind an import variable of the type (existscode C. (SatisfiesSignature S C * (X -> [C] Y))), where S is the import signature.
If a module has access to installed implementation code C and it knows SatisfiesSignature S C and SatisfiesSignature S C', then it can conclude C = C'. It can take advantage of this knowledge to get access to fuller knowledge about how an (X -> [C'] Y) function behaves.
"I was (and still am) waiting for you to teach them to me :p"
Really? I don't remember where we left off, but let's get in touch on this.