Monkey porting I

[lontivero]

No description provided.

[NicolasDorier]

@lontivero you may want to take a look at #696 from @joemphilips

I was planning to merge it, but I don't think anyone wanted to use it immediately, so I kept the PR open waiting for the opportunity.

[joemphilips]

I abandoned my attempt because miniscript/output-descriptor spec was continuously being rebuilt from scratch. So I'm happy if @lontivero is taking after me. I was exhausted by keep scratching my head around for prototypical miniscript.

My attempt was based on rust-miniscript, by I recommend to port from C++ version. It seemed more concise than rust version.

[NicolasDorier]

@joemphilips even the miniscript one if I understood is constantly changing? I thought the output descriptors were kind of stable.

[joemphilips]

@NicolasDorier The spec for the miniscript contained new version of output-descriptor and that was not stable when I was playing around. The restricted version of output-descriptor (which we already have in bitcoin-rpc) is stable, I guess.

[lontivero]

Ohhh! I didn't know about @joemphilips' PR. I've just scrolled up and down his PR and it looks good (that functional approach in the code is cool btw). I can take it and make some progress on top. I cannot promise anything but i will try.

[joemphilips]

Speaking of #696 , this contains the restricted version of output descriptor, which works fine and passes every tests in bitcoin-core. But if i could start from scratch, I will probably not use Parser combinator. functional parser combinator is a great tool in functional-first language such as F# but in C# it is hard to read/debug.