Document And/Or vectors contain 2 elements

[tcharding]

It is not immediately obvious that the Concrete::And and Or vectors contain exactly 2 elements, add code comment to document it.

[tcharding]

After #594 I might investigate whether it helps to remove the vectors all together. In miniscript::decode::Terminal we don't use vecs for ands and ors.

[apoelstra]

@tcharding that's because miniscirpt::decode::Terminal is part of Miniscript itself, which is never going to have n-ary ands or ors. The policy types are a completely different beast, and they're far less rigid in how we can change them.

[tcharding]

Do you mean policies are a thing that is still being improved but miniscript itself is more 'complete'?

[apoelstra]

ACK 47c8776

[apoelstra]

Miniscript is actual on-chain data. Policies are part of the "policy compiler" which is an entirely offchain tool used to produce efficient Miniscripts, and which has no guarantees about determinism or anything. As far as I know it isn't specced out or anything. So in that sense, yes, Miniscript is more "complete".

In another sense, that way more people care about Miniscirpt than care about this compiler thing, I expect more future work to go into Miniscript than the compiler. But that's just me :).

[apoelstra]

We also care much less about memory efficiency for the compiler, for this reason, which is why we have Vecs in there even though there are no immediate plans to generalize the ands and ors beyond binary operators.

[tcharding]

Awesome, thanks man.