Making a GTK application in Haskell, part 1 | Hacker News Reader

Making a GTK application in Haskell, part 1

floreal.tech

168 pointsVosporos51 comments

This seems to rebuild the entire view from scratch on every model update? Or is there some diffing magic that's not shown in the article?

This loses all non-persistent UI state such as scroll positions, half-entered text etc. etc.

Not really a workable architecture for a real app. React was invented because of this problem (how to make functional-style view building actually work...)

Is a widget a monad? Anyway, the examples in this tutorial are another proof that Haskell is the best imperative language!

It really is a great imperative langue! The IO monad is basically a better C, if you know how to wield the FFI.

It really is funny how you go through learning all these fantastic abstractions, and then at the end your line-of-business code ends up looking a lot like it always did. But expecting your data structures and control-flow functions to behave according to laws makes things so much more predictable and easier to wrangle.

>"Algorithms + Data Structures = Programs." — Niklaus Wirth

Widget is not quite a Monad, in this instance it's a newtype around a pointer and classes that mimic GTK's own class hierarchy.

No, a widget is not a monad. I think you should rather think of it as just the description of how to draw a UI - it's a GTK concept, not a Haskell concept.

Something that could be a monad is some sort of widget builder. You would be able to imperatively describe the construction of a widget. Then "running" that monadic computation would return a widget, or something along those lines. That monad would then most likely just be some sort of state/writer monad.

A GtkWidget is just a GObject in the category of C-style cast macros , what's the problem? :)

Replace `backdrop-filter` on `.backdrop::after` with `filter` on `.backdrop picture` for a free scrolling performance boost.

Indeed the scrolling performance is awful, makes reading it less enjoyable, especially when the topic is GUIs!

desktop and mobile browsers have a reader mode icon you can click. it is useful for 1) this 2) website blocking fully loaded content with some paywall popup 3) and more!

click it for a better time

"better time" = the syntax highlighting is gone and the code is no longer monospace?

Anyway, the website seems to be fixed now, nice!

Syntax highlighting does go, but at least on iOS the reader still uses a monospace font for the code blocks.

Are people still using gtk?

I started to learn it back then via ruby-gtk2. It was not the best experience but I learned several key things pertaining to widgets and the UI. Then came gtk3; it was in some ways worse than GTK2, but it also brought a few improvements such as the partial CSS support. I always miss that when I use e. g. wxwidget.

Then came GTK4 though and things changed. Tons of old things broke or no longer worked. Simple things such as main_window_widget.move(0, 0) for top-left positioning (I added an alias to this, .top_left in ruby and that worked nicely); there are work-arounds to get the old behaviour, but this is just one example of so many more things that were eliminated. GTK4 is a GNOMEy-toolkit and GTK5 will be even worse since it will be wayland-only.

"Interacting" with the GNOMEy-GTK devs is a total waste of time and I am hardly the only one who had that experience. For GNOMEys it may be a useful platform, but GTK no longer is a general toolkit really, despite claims by the current GTK devs otherwise. Why would we non-GNOMEys want to keep GTK on life support? There really needs to be a toolkit that can work in a much more de-centralized way. Sadly I also don't have a good idea here, since funding is an issue and GUIs seem to have taken a huge hit ever since the world wide web became dominating.

McCLIM is better

Well, it is what was always considered to be a default toolkit. Sure, I like Qt and prefer such apps but you got a have the GTK installed anyway. It was always difficult to have general toolkit with it when you depend on dozens of dependencies, collection of libraries, not big fat libraries like in Qt, that you can deploy.

GTK4 changed a lot though, like they do not even try anymore, deprecated font dialog because that is better done with XDG portals, but such thing does not even exist. How will that work on macOS and Windows, it cannot? Or what they did with the menus. Toolkits should be user oriented and should not have vision, it just needs to work and provide controls, events, etc., you cannot even position windows in macOS and Windows with GTK4, that is not toolkit that works for users.

I am working on the IUP fork here https://github.com/gen2brain/iup-go , one toolkit to handle them all, and I did my best for GTK4 backend, but from 14 drivers/backends I worked on, it was the worst experience and I had to fight battles with it.

GTK2 tried to be more general-purpose, while GTK4 is more about serving the vision of Gnome the platform.

I hope that, if desktop / laptop as a platform remains, there will appear an interpreted, platform-independent toolkit / language for GUI specifically, along the lines of Tk, or QML, but much lighter weight than HTML+CSS.

GTK3 has nice, conventional looking interfaces. Developing for it always felt insane, but the advent of AI has completely removed the friction so I've had Claude build me quite a few apps using it because I like the look and it's easy to navigate.

> Are people still using gtk?

Manifestly yes. There's even a list of GTK4/Adwaita apps available here: https://arewelibadwaitayet.com/

I will continue using GTK until QT decides to stop being ugly (by default).

Qt is ugly only when you don't have aesthetical taste. Here are my Qt apps:

https://www.get-vox.com/

https://www.get-notes.com/

Not to offend anyone but those apps still look and feel like QT apps. Not particularly pretty

I'll take the criticism but can you please be specific and constructive? What exactly look and feel like Qt apps? What's not pretty?

What makes them look like QT apps ? To me I can't see anything identifiable, they look like generic web apps with a mac OS border.

I don’t think the apps are ugly at all but the kerning of the first letter of the headers feels very off on the website. Maybe it’s intentional but I find it distracting and inappropriate for a note taking app. (latest iOS, Firefox, iPhone 17)

You might want to add the `playsinline` attribute to the videos on get-notes.com. Each video opened in fullscreen for me after the previous was closed and I had to dismiss them all before reading the website (iOS)

> import GI.Awd qualified as Adw

please tell me that's a typo

possibly enabled by lsp (Adw.foo -> "foo found in GI.Awd, import it with the name you used?")

yeah seems to be a typo, it is "Adw" and not "Awd", phew

https://hackage.haskell.org/package/gi-adwaita

i've been writing Haskell GUIs for a few years and mostly stick to react-banana or reflex because wiring up gtk-gi signals manually gets messy fast. The Elm architecture pattern here looks clean on paper but I'm curious how you handle async events from the widget tree without ending up in callback hell. Did you end up wrapping all GI callbacks in a channel that feeds into your update loop?

Is Haskell in this case just binding a local HTTP port that users then hit with the browser? Or is it like a Tauri/Electron type of thing?

It's a native desktop app, so none of the above.

I haven't seen anyone write about wiring FRP systems to traditional GUI toolkits. Do you have a blog?

bro takes 2 years to make a todo list

Just keep in mind that some people like me avoid Haskell and the huge package mess it causes on Linux. Pandoc is infamous for that. Just stick to C++.

That is entirely your distribution's fault. ArchLinux has a user-hostile packaging approach which I do not experience in Fedora.

I completely avoid any haskell package in Arch and just build it with Stack, it's usually simple.

What does Arch do in particular to cause a mess? It's been a hot minute since I last used it and surely didn't use pandoc back then.

They build and link all Haskell libraries dynamically.

Haskell packages in arch are dynamically, rather than statically, linked, which pulls in a large amount of transitive dependencies (reportedly in the neighborhood of a gigabyte). The maintainer has a pretty reasonable (to my eyes) explanation[1] as to why this is the case, but admittedly if I were an arch user I'd probably find it a bit annoying.

[1] https://www.reddit.com/r/linux/comments/9emwtu/comment/e5qss...

Arch Linux approach to python/haskell packaging is a great case study of what not to do...

Quite right, indeed

It even puts pressure on Linux package managers to support special mode where packages are handled by pacman intead.

Can confirm, every time I run `pacman -Syu` and see a hundred `haskell-foo` packages being updated I think "Oh yeah, those are all dependencies of that one app I still use. Got to remember to find an alternative, then I can stop getting lost in a maze of twisty little packages, all different." But I never do remember to switch away from that app.

I'm sorry this is your experience. Considering that by default GHC (the Haskell compiler) statically links Haskell dependencies of an application, this is a subpar way of doing things that your distro's packagers have decided to inflict on you. I won't tell you to migrate, but Archlinux has been one of the worst PR for Haskell in ages. :(

Does your distro not statically link Haskell libraries the way it’s meant to? Installing pandoc only requires libgmp.

Archlinux is (in)famous for not doing so

Good thing I don’t use Arch.

My Haskell experience on NixOS is wonderful!

I think it depends on your district. On some distros (looking at you arch!) I think GHCup and keeping things in /home and out of your system package manager is the better approach.

That said, I never had issues with Pandoc on any distribution. But I have struggled with Pandoc extensions, before I got NixOS (and flakes).

On the one hand, NixOS can have a steep learning curve. (Although if you're willing to use LLM coding agents, I bet "steep learning curve" turns into "be curious and ask the LLM how it works").

On the other, I bet anyone curious about Haskell would love NixOS.

In regards to Haskell not being trouble, though: I'm not too familiar, but I thought stackage & the 'stack' tool would ease over any pain.

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