Courts can't compel you not to talk. They can merely punish you after-the-fact.
So if you're talking about "everyone in a giant group of people" and doing it routinely, existence of those secret subpoenas seem like they'd get leaked eventually. Especially if it's hard to tell which of the 300 people leaked it.
Every time these hit the news, the exchanges harden their defenses. That's good for holders of Bitcoin, but I wonder if usability for small transactions is hurt.
I asked someone with no prior Bitcoin experience to test a checkout process with Bitpay[1], and the 3rd[2] time they had to pull out their phone they were really frustrated at all the steps. Plus, doing that many on-chain transactions is going to add a 30% overhead to a common purchase.
Am I wrong to advise users interested in single <$100 transactions to skip all the apps and use their exchange's wallet? I hear a lot of people recommending that everyone operate their own wallet. But since this page is in Bitpay's checkout funnel the wallet must be very important.
There's theorem provers like Coq. I'm pretty comfortable with Haskell, but concepts like the difference between Propositions and Booleans are enlightening to my Haskell the same way Haskell can be enlightening to use of other languages.
Haskell and ML at least have advanced type systems. Since types are erased during compilation, you can't reason about type systems in terms of their impact on the generated code. An example of a simple type system is C with its structs.
Haskell also has lazy evaluation, which is very difficult to do in C. Obviously you could encode your own trampolines, but at that point you might as well be coding in a Turing tar pit language "where anything is possible but nothing of interest is practical".
Pattern-matching and ADTs are also usually difficult to do in other languages.
Most of the benefits of something like Haskell only show up on larger projects, so it's not meaningful to point to specific language features as a point against it. I can do just about anything in C. The type systems you probably can't do; you'd have to embed a language and that doesn't count.
I'm not sure I like LYAH as a practical resource: It's silly and might put people at ease, but I wouldn't feel comfortable writing a database or parsing tool or compiler after reading it.
Real World Haskell is better for these, but is a little dated by now.
So if you're talking about "everyone in a giant group of people" and doing it routinely, existence of those secret subpoenas seem like they'd get leaked eventually. Especially if it's hard to tell which of the 300 people leaked it.