But I view parser combinators in the same lens as lenses, another powerful approach to solving a specific problem that is unlikely to receive mainstream recognition because of all the Haskell.
new = copy(old)
new.foo.bar.baz = new_baz
return new
It won't come out of Haskell because it's uniquely a solution to a specific Haskell problem. Mutating a fresh copy through a "lens" when you have `=` is a level of geekage that cannot become mainstream.Some of the other ideas from lenses are becoming mainstream, like the .? conditional accessor in e.g. C# and EcmaScript.
The idea of ?. was there since the beginning of times. You don't have to dig deep to realize that (x ? x.y : nil) and (x ? x : y) sucks. Even gnu C had (x ?: y) for quite a while. It's just that the designers of to-become-mainstream languages all start with the same "density" and ignore the damn obvious, and then rather than fixing it, chew on the same dilemmas they all inevitably introduce. I sometimes wonder if they have written regular code at all or started inventing languages right after school.
Lenses and more generally optics are a lot more powerful than just dot-accessors. They are closer in spirit to XPath or jq, except that they are general enough to work on most data structures, not just XML or Json.
Hmm, anything else you have in that list I should be looking into? As I also agree they are two of the most interesting things I got from learning Haskell. (Along with type driven reasoning, monoids and functors).