| ▲ | yen223 9 days ago |
| I would be very happy to be proven wrong here. 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. |
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| ▲ | wk_end 9 days ago | parent | next [-] |
| FWIW lenses are lovely in Typescript with monocle-ts, and extremely useful when - speaking of functional ideas hitting the mainstream! - writing Redux reducers to provide updates for immutable data. |
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| ▲ | wruza 9 days ago | parent | prev | next [-] |
| It's unlikely because people don't get why jump through so many hoops when you can 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. |
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| ▲ | kqr 9 days ago | parent | next [-] | | This is a common misconception. Lenses (or more generally optics) are not limited to targeting single fields. They can target composites, alternatives, etc. They go way beyond a normal accessor dot and can do stuff that cannot be done in mainstream languages. Some of the other ideas from lenses are becoming mainstream, like the .? conditional accessor in e.g. C# and EcmaScript. | | |
| ▲ | wruza 9 days ago | parent [-] | | They don't surpass Turing Machine level, so I'm not convinced. 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. |
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| ▲ | yen223 9 days ago | parent | prev [-] | | This comment proves my point about how "all the Haskell" hinders mainstream adoption of a thing. It's very easy for folks to miss the point of the thing! 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. | | |
| ▲ | wruza 8 days ago | parent [-] | | It doesn't. "All the haskell" is your protective decoy against "it's not that useful when you're not chained to the wall". Show me a lens with a bunch of other fp tricks and I'll write dumb inline code for it that does that same thing, but without twisting anyones brain or trying to not miss its thin point. |
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| ▲ | BoiledCabbage 9 days ago | parent | prev [-] |
| > But I view parser combinators in the same lens as lenses 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). |
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| ▲ | yen223 9 days ago | parent [-] | | The big one that springs to mind, though it's not a Haskell idea, are algebraic effects and effects handler |
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