The one I know about is Pandoc, which I use every day.
xmonad. Some websites usable as applications using yesod maybe. (Shellcheck - great but doesn't count, you use it for programming a computer).
What else are we missing. The list is not to bash Haskell, it's is instructive to be aware of a pretty significant data point and understand /why/
edit: Please note that libraries are /not/ applications but the two are conflated here (accidentally?) obscuring the point: https://wiki.haskell.org/Applications_and_libraries
https://github.com/bazqux/bazqux-urweb/tree/master/crawler
Off the top of my head I also know of Freckle (https://www.freckle.com/) and Co-Star (https://www.costarastrology.com/).
More importantly, this is not a Haskell book! I'm sure the author would be happy to see these ideas applied using Javascript or Scala or Java 14 or anything else.
> Haskell is considered a difficult language to learn, which is certainly true if you come from traditional procedural languages. But rest assured, this is not a Haskell book. You won’t need more than a passing understanding of the language’s syntax and a few high-level idioms. Everything you’ll need to know will be shown later in this section. The ideas present in these pages are adaptable to any piece of technology you’d like, though they might require strictly more discipline to maintain than is necessary in Haskell.
- Chapter 1.3.1, page 6
I'm not going to try to list all the user-facing applications written in any functional language, but I'm sure we can agree it is a much longer list.
If it's /hard/ to use the language you have chosen for your book. Which is also the most prominent language in the space to write useful stuff then you need to address that right there on the landing page. Yeah? Is that not reasonable?
The Haskell list is very short. Why? Why is this a solution to that problem? Why is it not just yet another burito-like analogy for monads?
Frozen-bubble was great, slick and fun at least 15 years ago and is written in functional perl.
He's clearly trying to solve the Haskell problem of "We can't write apps" here. He says so.
Do you have the same issues with SICP using Scheme?
Finally, since this is Hacker News, I'll appeal to authority with Paul Graham: http://www.paulgraham.com/avg.html
> Another unusual thing about this software was that it was written primarily in a programming language called Lisp. It was one of the first big end-user applications to be written in Lisp, which up till then had been used mostly in universities and research labs.
At the time, Lisp was 40 years old.
I'm pretty sure Abelson and Sussman would have had an honest, will reasoned and nuanced answer as to why lisp had not replaced fortran and whether it will or even should. Those guys didn't go for rank boosterism.
Why no lisp? People didn't /own/ computers they could do what they liked with. You needed permission. Ask bill gates about that, he'll tell you... How could you hire lisp hackers? Not an issue for Paul. Done.
There are tens of thousands of us who learnt Haskell (and then maybe wrote a monad tutorial). How many applications? This tells us something. What?
The author has a theory.
The author has written a tutorial.
Show me the application!
Why does that make it not count? Not every language needs to be used to write enterprise software.
This is a useful metric for someone considering programming technology to get something done rather than to learn something. (The "learn something" case here is fine. If you're thinking of it, definitely do it. Learn FP. Learn Haskell. It's useful for your mind and fun!)