Hacker News Reader

Hacker News

Comment by CyberDildonics | Hacker News Reader

Full thread

CyberDildonics

Is there any fully formed application made with Haskell out there?

View on HN

Pandoc, the "universal document converter", is a good example of a large, feature-complete Haskell project in wide use.

https://pandoc.org/

Most people who use it aren't aware it's written in Haskell!

Here are a few:

elm: https://en.wikipedia.org/wiki/Elm_(programming_language)

purescript: http://www.purescript.org/

postgREST: https://postgrest.com/en/v4.1/

Trending stuff on github: https://github.com/trending/haskell?since=monthly

Those are languages

The Elm and Purescript compilers are written in Haskell though.

The examples mentioned in the other posts confirm my impression that Haskell is a good language for text processing and server applications but a pain for writing rich desktop applications.

One of the things I miss in Haskell is a way to compile to C, and a convenient declarative GUI which also compiles to C so that all code can be linked together, and distributed as a single binary. The GUI doesn't need to be native. Lisp has its own GUI (McCLIM), Smalltalk has one (Squeak), Rust has one (Conrod), why not Haskell?

I think pretty much any Language is a pain to write GUIs in, a single property dialogue in photoshop is ~6k loc in C++...

Pascal (Delphi, Lazarus) and Visual Basic are exact counter examples. They demonstrate how easy and convenient GUI development can be.

I really hope I'm wrong, but if you're talking about VB.NET, then my personal experience with it has been the exact opposite of easy and convenient.

Edit: Okay, good, VB.NET is probably not the Visual Basic you were talking about. Thanks for the history lesson!

Why would some ridiculous plug in API mean that every language is a pain to write GUIs in?

Red uses DSL's to make it pretty easy. It's a REBOL-like language that's easy to parse and macro kind of like LISP. Here's an early demo of how that looks with examples:

http://www.red-lang.org/2016/03/060-red-gui-system.html

I don't know Haskell but I know Galois does DSL's like Ivory language with it. So, I imagine doing something like Red's GUI in Haskell would be worth exploring. Alternatively, building such a clean abstraction on top of a cross-platform library with messy stuff generated automatically from DSL version.

I'm currently playing with Reflex, a wonderful functional reactive programming library that lets you compile the same code into into webapps with GHCJS (a JavaScript backend for GHC) or into standalone desktop apps (using WebKitGTK).

It's wonderfully expressive and doesn't feel like you're painfully imitating C++ in Haskell. On the contrary, it's very idiomatic.

https://github.com/reflex-frp/reflex

However, FRP is ... unusual, and takes a bit of time to get the hang of.

Here's a stripped-down todo app "tutorial" in Reflex:

https://gist.github.com/mrkgnao/1a5c06cc1e188f2238c8c11cb74e...

And this is a full-featured TodoMVC in Reflex:

https://github.com/reflex-frp/reflex-todomvc

FLTK is a GUI toolkit that has Haskell bindings. It's a very C++-like API, but the library is in heavy development.

https://github.com/deech/fltkhs

The developer is also quite friendly, and I believe there are good docs. Here are a few demos:

https://github.com/deech/fltkhs-demos

Also, GHC does have a C backend, afaik, although it's deprecated nowadays and only available if you build it yourself in "unregisterised mode", which people do when porting GHC to a new architecture.

To be fair. Good desktop applications pretty much require teams and are more about user acceptance than metrics you can capture in the type system. Or tests.

Most rich desktop APIs are very imperative and the Haskell bindings are often just a thin veneer on top. For an example of a really nice Haskell UI API, see threepenny-gui:

https://github.com/HeinrichApfelmus/threepenny-gui/blob/mast...

Besides the example stated here, there is also shellcheck: https://www.shellcheck.net/

GPU Database SQream DB's (http://www.sqream.com) main component is Haskell based, in two parts:

1. The open source SQL parser - HsSqlPpp https://github.com/jakewheat/hssqlppp, 35700 LOC + 3900 LOC of tests

2. The compiler and optimizer (proprietary) is roughly 55,000 Haskell LOC

Edit: And we use Pandoc and Quickcheck internally for a bunch of different things

Besides pandoc: xmonad, hledger, git annex, gitit, hakyll and probably quite a few more ;)

People have mentioned a few here, but I'd say that Haskell's current ecosystem is much more directed towards building infrastructure than user-facing apps. Indeed, most popular Haskell programs are command-line utilities rather than "applications" in the modern sense. Most companies that use Haskell also use it to make robust infrastructure rather than, say, user-facing apps or webpages.

I think it's hard to find many modern applications (I.e. some software package with a UI) made in anything outside of a few choice languages like JS, C++, C#, or Swift.

https://www.quora.com/What-is-the-largest-commercial-program...

I implemented a fractal zoomer, but it might be too simple to meet your vague "fully formed": https://github.com/serprex/Fractaler

llpp, depending on your definition of "fully formed".

And there is/was a tiling window manager, but everyone I know who used it at some point migrated away because the configuration was Haskell as well.

Xmonad!

Still use it with gnome and it's the only reason I can half read Haskell!

llpp is (mostly) written in OCaml.

still using it. only tiling wm I've found that plays well with desktop environments.

Pandoc, I use that heavily for homework.

hledger: http://hledger.org

Reply on news.ycombinator.com