Haskell2020 Is Dead, but All Hope Is Not Lost (2019)
reasonablypolymorphic.com
reasonablypolymorphic.com
If you're interested in Haskell and are doing web dev, check out IHP, Haskell's version of Laravel/Rails/Django: https://ihp.digitallyinduced.com/ (Disclaimer: I'm founder of the company that makes IHP)
I'm pretty fluent in Haskell, but finding Haskell jobs is hard compared to OCaml or F#, which are a bit of a niche of their own. Actually, I routinely get OCaml offers when advertising Haskell on my CV. I find this interesting and exciting as OCaml was not very frequent outside academia a few years back.
Long statements, but I really do think employee retention and personal fulfillment would lead to a better working environment. So that is the way I’d argue it. Obviously a comprehensive sampling of performance metrics would be needed along with the more HR reasonings, but I think there are plenty of examples where Haskell is performing acceptably.
Looks like a good way of getting back into experimenting with haskell.
post <- fetch postId
>>= fetchRelated #comments
As you mentioned you're consuming the data with a JS frontend: For these cases we added a subsystem called DataSync to IHP. DataSync allows to use the IHP query builder directly from the JS side. This way we basically avoid needing to hand-write these nested graph API responses. Complex forms that depend on a lot of complex data can now be implemented using React components.
Here's an example query call from the JS:
const todos = await query('todos')
.where('id', 'd94173ec-1d91-421e-8fdc-20a3161b7802')
.or(where('id', '173ecd94-911d-1e42-dc8f-1b780320a316'))
.fetch()
You can find an example of this here: https://ihp.digitallyinduced.com/Guide/realtime-spas.html#bu... For web apps that are fully consumed by a single page app, we're right now building IHP Backend, which provides the IHP tooling + the DataSync API in a way that is way simpler than full stack IHP. If you're curious, you can find a demo video here: https://youtu.be/-jj19fpkd2c
Is this a language specific thing? Syntax? Underlying implementation of the language?
Is it a missing abstraction in the language?
I'm sure its possible to build something that compiles, but it would be so awful to use that you are better off with hand-written SQL where you need it, and N+1 stuff where you can get away with it.
I presume that the accessors in Haskell would be 1-1 with SQL language requests, but the problem is that SQL queries are not typed? Or are dynamically typed?
So, instead of a generic library for SQL queries, one would have to implement a library for a specific SQL DB structure?
So if you have a companies table joined to a contacts table, you'd get a two element tuple with a list of companies and a list of contacts, and then you have to iterate to do the joins and turn it into a JSON tree.
And there is no help at all for wanting to take in a tree of JSON data, and turn it into updates to existing records and inserts for new records.
You could have a library that to knows how to return a tree if you define a typeclass for the tree, but the only way I'd know to do it would be a separate tree data type for each result set. In Ecto you do have to define a structure that knows all the possible associations, but which associations you actually load in any given query is flexible, you can have associations that are not loaded eagerly for one query, and loaded eagerly in another. In Haskell I can't imagine doing that without two different tree structs, because there is nothing that would know how to take two differently typed result sets and make the same tree partially loaded.
Esqueleto has a function to avoid n+1's and return a map now:
https://hackage.haskell.org/package/esqueleto-3.5.3.0/docs/D...
https://www.foxhound.systems/blog/grouping-query-results-has...
https://hackage.haskell.org/package/rel8-1.3.0.0/docs/Rel8.h...
module Main where
import Rel8
import Data.Int
import Hasql.Statement
import Hasql.Session
import Hasql.Connection
import Database.Postgres.Temp
main = Database.Postgres.Temp.with $ \db -> do
Right conn <- acquire (toConnectionString db)
flip run conn $ statement () $ select $ do
q1 <- many $ do
r1 <- many (values [1 , 2 :: Expr Int16])
r2 <- many (values [3 , 4 :: Expr Int16])
values [(litExpr "one", r1), (litExpr "two", r2)]
q2 <- many $ do
r1 <- many (values [10 , 20 :: Expr Int16])
r2 <- many (values [30 , 40 :: Expr Int16])
values [(litExpr "ten", r1), (litExpr "twenty", r2)]
values [(litExpr "X", q1), (litExpr "Y", q2)]
> main
Right (Right [("X",[("one",[1,2]),("two",[3,4])]),("Y",[("ten",[10,20]),("twenty",[30,40])])])One if the things Haskell is best at is parsing and the resulting data structures are very nested.
What is an example data structure you think Haskell would struggle with? What language wouldn't struggle with that example?
I just lost a big block of time because of this, please contextualize correctly that claim when you make it.
Support for dot-notation like it's documented at the proposals has been partially added. Field fetching is complete, field updates isn't released at all. It is being actively developed, and both bring very interesting features that you can't get in most languages - after all, it's Haskell - but it was only partially released up to now.
Sure, a new Haskell standard would allow for more compiler competition and that's a good thing, but it cannot fix the language. I think what we really need is a new language that picks all the good parts from Haskell, but has a very small syntactical core. Something like Go, but purely functional. You might say Rust or Elm. But Rust is too performance oriented and already quite big, hence more like a C++ replacement. And Elm is too domain specific and maybe a bit too simple (lacks ad-hoc polymorphism).
So maybe a general purpose Elm like language with ad-hoc polymorphism, but not as complex as Purescript, with a GC that compiles to binaries and WASM with a standard code formatter and very conservative regarding new language features, just like Golang.
This doesn't quite make sense to me because Haskell and Go are kind of polar opposites. Also many would say you are describing Haskell98 I think.
I disagree. C++20 is a standard, even if it is ugly and terribly complex it is being implemented by three separate compilers. And look at Javascript. The attention given to it is starting to show, making the language neater than in the past. The task is not straightforward but the point of the article is that there is absolutely no manpower ready to do it. I think that a few dedicated people could do the work well.
I sometimes think that not enough people appreciate the tough spot that C++ was in around 2008 and just how far it has come since then. The additions via evolution to C++ have been far beyond what I would have thought possible. IMO, the 3 year release cycle is just the right pace.
Yes, I know the language has become complicated and there are still a lot of rough edges. But it's a model of change that's worth emulating.
I'll wait patiently until people start asking for more language features, like the ten thousand last times... every widely used language ends up converging towards at least C++-levels of expressiveness (Java, TypeScript, Go, Python with static types, Caml, etc... you name it) because it turns out that those features are actually needed.
You could get everything done with Javascript's prototype system that you wanted done with classes.
You can get everything done with Go's interfaces (and a bit of boilerplate for the edge cases) that you can do with generics.
The problem is that people come to this language from other languages, and have expectations that this language is basically the same as the other language they already know (and if not, why not?). There's a constant pressure on languages to conform to a single set of "known good" conventions [0]
The unusual languages are needed because we need that diversity, but they are never going to be "mainstream" until/unless a Java dev can learn them inside 3 months without challenging any of their assumptions about programming.
[0] the classic is Erlang vs Elixir - Erlang is "weird", Elixir is "awesome"
> You can get everything done with Go's interfaces (and a bit of boilerplate for the edge cases) that you can do with generics.
by that logic why don't you just use lisp for everything ? it's been there since 1958 and you can also get everything done with it, including reimplementing yourself a Go- or Js-like DSL if you allow yourself a Racket.
The truth is, your "get everything done" actually does not include everything, because "writing less boilerplate" is not only a feature, but one of the most important ones. Boilerplate is unambiguously bad and a place where terrible bugs hide - any time you can replace it by something with much less chances of bugs, such as a language feature, you should (and I'd argue it's professional malpractice to chose not to when you have the option).
Or using Eclipse EMF to read UML interchange files generated from Rational Rose and generate the boilerplate for Java applications, before generics and compiler plugins were a standard Java feature.
When languages aren't feature rich, someone will eventually start writing that boilerplate, hence why //go:generate exists, despite the fact that Go people telling writing boilerplate is not a problem.
There's a seemingly inevitable tradeoff between complexity and bugs. Low complexity tends to lead to repetitive, simple, avoidable bugs. High complexity leads to unique, hard to reason about bugs.
I find the preference for simple vs complex code has to do with what kind of bugs programmers want to troubleshoot. Some prefer simple and repetitive bugs, others prefer fewer, more difficult bugs.
As a heads up to anyone reading, you may not consider it only 'a bit of boilerplate'.
How far it’ll go, and if it’ll ever get traction is fun to observe.
But yes, the entire community will need some time to get together into any new idea.
Haskell users have strong opinions about language syntax- I suppose moreso than your averaged user base. It may take a generation as Doug crockford says for those options to die and retire so new ones can come take their place. Looks like that still holds.