@jorge_jbs Even purely functional programs *do* get access to side effects though, because you need to do do anything useful. They do it through a monad.
The question is: who gets access to that monad?
You're right that functional programming can help, but it isn't that the language is functional itself that does it, it's that it supports higher-order functions and the ability to pass around references.
@cwebber If the library's interface doesn't return any monad (for example, isPasswordStrong has type String -> Bool) then there is no need to give access to any monad, everything is pure.
This library seems like a good fit for a pure library. If it needed some types of side-effects (but not all) you could return the FileAccess monad, or something similar.
All the code has access to all the monads. Executing them is another story.
@jorge_jbs You may be right that this is protecting the right behavior/safety. The way you described it, you can only perform side effects if you've explicitly been handed the reference, does sound like exactly the reference-based-ocap-security stuff I'm talking about. That approach isn't limited to purely functional languages, but you've correctly identified a purely functional way to do it.
@cwebber I don't know how ocap works, but yeah, it looks we're saying the same thing but implemented in different ways.
@jorge_jbs I suspect you would enjoy reading http://mumble.net/~jar/pubs/secureos/secureos.html :)
@jorge_jbs @scolobb @cwebber
I could imagine pure functions leaking information about passwords via timing channels, CPU heat, fan rates, EMF levels related to frequency of RAM accesses, etc. Functional code eliminates state from the perspective of the programmer but in some respects only hides state that still exists from the perspective of physics.
@enkiv2 @scolobb @cwebber Well, you could make a functional language that abstracts over all the implementation details, so you couldn't rely on them. For example, the implementation could add noise so that it really is pure. But, in practice that sounds to be terribly slow xD. But, also in practice, you wouldn't leak side-effects that way.
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