by scscsc on 4/12/23, 5:32 AM with 110 comments
by yamtaddle on 4/13/23, 5:05 PM
It's sometimes implied that those who trip over Haskell just aren't big-brained enough to understand various important concepts related to it, but I've found they're usually very easy to grasp, provided the explanation's not using Haskell examples. If all programming were Haskell, I probably never would have become a programmer in the first place. Would have taken me too long to figure any of it out, probably would have concluded I wasn't smart enough to be a programmer.
I do wonder if there are some shared experiences or common patterns to who tends to love Haskell, and those who don't. I also feel nigh-dyslexic trying to read math formulas. Human language and broadly C-family programming languages, on the other hand, seemed easy and natural to me, almost effortless to pick up. Wonder if there's a "mathy"-person versus "languagey"-person divide on finding Haskell legible.
I'm not sure it's the whole thing, but I think I've also figured out that I find algorithm-type reasoning far easier to follow and work with than equations or proofs. Like, the only way I can begin to get traction with an unfamiliar equation is to break down what each term and operation "does" to something "moving through" it—it's tedious as hell. Might be something there.
by javajosh on 4/13/23, 4:45 PM
Instead of building on this reality, Haskell asserts that the starting point is not physical reality, but rather a mathematical formalism called "The Lambda Calculus", the physical machine is looked at with disdain and pity, its limitations to be worked around to provide the one true abstraction. This is the original sin of Haskell, because it is an attitude that isn't driven by a need to make a thing, but aesthetics and a peculiar intellectual dogma around building that ultimately becomes a stumbling block.
In my view, you have to respect the machine. Abstractions can be beautiful, but they are ephemeral, changeable, unreal. The danger is that these illusions become a siren song to makers who are always looking for better tools, and to these makers the abstractions become realer than the machine. Haskell's power users famously don't actually make anything with it (modulo pandoc and jekyll), and my guess is because either they find that 90% of real-world things you want to do are "ugly" from Haskell's point of view, and so are left as distasteful "exercises for the reader", or they get so distracted by the beauty of their tools they never finish.
In any event, Haskell is a road less traveled for good reason.
by mrkeen on 4/13/23, 4:00 PM
> There is also a school of thought that you should start Haskell by teaching the IO monad first, but I am not convinced: in my experience, if someone gets exposed to IO early on, they will contaminate all their functions with IO. They will essentially end up writing Java in Haskell.
I don't think this is such a bad starting place. Crawling before walking. Purifying an (unnecessarily-) IO function into an ordinary function is a good exercise.
Trying to enforce non-IO from the start would be like enforcing 'no new keyword & factories only' in another language.
by mprovost on 4/13/23, 8:32 PM
For example, to implement a simple "hello world" program in Rust you have to use a macro (println!), so you can't even look for a function signature in the standard library docs to help. So you can either just say "don't worry about this for now, just trust me" or spend a whole chapter diving into macro syntax. The number of concepts you need to implement a basic program is pretty large and you could easily spend a chapter going into any of them.
Personally I'm not a fan of the approach in this post to just "lie" to people but I do find myself showing a non-optimal implementation because that's all the syntax I've introduced up to that point. Then later I show how to do it better. I know some readers just want the final answer up front though.
by agentultra on 4/13/23, 5:10 PM
One of the reasons the standard Prelude includes partial functions and specialize versions of `map` and `filter` is to support the pedagogical use-case (as far as I understand the situation). Most production applications will use a custom Prelude of some kind in order to prevent programmers from using foot-guns like `head` or make things more general in the case of `map` and `filter`.
Turns out using linked-lists for everything isn't the best idea but a lot of Haskell applications will use them because it's in Prelude.
Bit of a balancing act supporting both use cases.
by yakshaving_jgt on 4/13/23, 5:48 PM
It compiles quickly, the guidance offered in error messages are best in class, it's small, and the mental model is consistent.
In fact I think it's far easier to learn Elm (and also perhaps web UI development wouldn't be such a shitshow if programmers earlier in their career used Elm to build their mental model) than it is to learn:
- React
- Redux
- Immutable.js
- Lodash/Ramda
- ES${CURRENT_YEAR}
- Webpack/Parcel/Grunt/Groan/Whatever
- etc…
I've seen so many early programmers go through some React course thinking they've learned FP, and yet struggle to solve basic problems by applying functions to values.
by tikhonj on 4/13/23, 5:20 PM
1. Using an online editor with a rich built-in library removes any toolchain problems.
2. A custom standard library simplifies pedagogically unnecessary details like Foldable
3. The custom standard library also avoids currying (f(a, b) for functions rather than f a b)
4. Custom error messages improve the feedback students get from the compiler
I would highly recommend Code World to anybody looking to teach programming with Haskell. If you want to teach Haskell in a way that fits the existing ecosystem, it's also possible to run Code World without the custom standard library[2].
[1]: https://code.world/#
by tome on 4/13/23, 4:45 PM
foldr k z = go
where
go [] = z
go (y:ys) = y `k` go ys
foldr k z = foldr_k_z
where
foldr_k_z [] = z
foldr_k_z (y:ys) = y `k` foldr_k_z ysby asplake on 4/13/23, 4:35 PM
by jy14898 on 4/13/23, 4:31 PM
Of course PureScript has it's own downsides not apparent in GHC
by iamnotsure on 4/13/23, 4:50 PM
I don't think this article is helpful for beginners.
by deafpolygon on 4/14/23, 5:49 AM
by FpUser on 4/13/23, 5:43 PM