Vanessa McHale

> What kind of project would be a sweet spot to ATS?

I'd say a large mission-critical C codebase that decides to grow and expand a formally-verified kernel of its most important functionality - it can be a real-time sytem, an OS kernel, a HFT algorithm etc.

Nowadays people seem excited about gradual typing in widespread dynamic languages like JavaScript and Python, because it allows them to adopt the best parts of static typing without having to rewrite the entire codebases in new langauges. Now imagine that you can introduce gradual formal verification to your battle-tested C codebase, without a loss in performance[1] and without forcing you into a new tooling ecosystem (compiler, debugger, profiler etc). Actually, you don't need to imagine it, because that's what ATS is :)

> I would love to understand the nature of the theoretical advantage ATS has here over Rust.

I'd say it's a synergy of two key features, that produce miracles when put together - 1) direct and safe pointer arithmetics [2], which enables the same data structures and optimisation tricks available in C, yet in a verifiable environment, and 2) refinement types [3].

> Would it be comparible with F*

Unfortunately, I don't know much about F*, MS Research regularly releases a new PL prototype after the other and I lost my count on Koka[4].

> ATS seems to be very much a concept/language in R&D phase. Its ergononics are difficult ergonomics (have a look at the error messages), documentation and example…

This comment misses the point of the article, which argues against a urban legend that Haskell is too difficult "unless you are this tall" (a Phd, an E.T., a superhuman). I also had a shot at explaining why people are already tall enough in a past short "comic strip" [0]. I think the article makes a good job re-assuring the urban legends are a myth.

Now. there are many reasons why one would want to use Haskell. For instance, to have fun, to understand better some pattern, to write expanding-brain memes, or, because they are good at solving problems with it. It is fine if your reasons do not intersect with other people's reasons. You can try finding answers whether Haskell matches your reasons in some other essays [1,2,3]. Maybe it is true for many people that their needs and desires are entirely covered with their own toolset. As a curious/optimistic person I find it incredibly pedant to say I'll never ever need to learn/use something (there's different goodness in everything).

Personally, practicing Haskell led me to appreciate the importance and trade-offs that occur when isolating/interleaving side-effects. Similarly, it gave me some vocabulary to articulate my thoughts about properties of systems. Both are super important in the large when you architect softwares and systems. There are other ways to learn that (e.g., a collection of specialized languages), but at least for me, Haskell helped me build an intuition around these topics. That said, the prevalence of…

> Does it actually succeed though?

Not sure about J, but I feel APL certainly does, at least for me - the symbol set makes it very easy to sketch out a solution.

Part of that ease is the generality of the various operators. That is the reductions and cumulative prefix can be done with any function. For example ⌊\ as cumulative min - useful as Vanessa McHale shows <http://blog.vmchale.com/article/numba-why>

kspalaiologos also shows APL enabling mathematical understanding on her blog <https://palaiologos.rocks/>

An APL equivalent of the J is +\¯1 1[(?100⍴2)] although others exist as there's no exact equivalent for J's
{ - see <https://aplwiki.com/wiki/From>

> it becomes easier to shoot yourself in the foot (which is mentioned in the alternative title, but doesn't seem to be expanded on much) -- say, by closing a Handle

lazy I/O (such as file reads) is suspect and even bad, but laziness + IO (or something like it) is a great way to stream from an API: http://blog.vmchale.com/article/lazy-io

Makes it possible to transcode for one. Basically makes streaming "compose" nicely - bzip2 and lzip otherwise have very different ways of streaming! And one would have to line a lot of things up.