[arbsn]

What confuses you about using Haskell for writing Web/Desktop/Mobile apps? System.IO exposes all the primitive input/output functionality one would expect in Swift, Python, or PHP, and there is an abundance of higher-level libraries for networking, parsing, graphics, etc. Haskell even has a fairly usable C FFI.

Haskell is a general purpose programming language.

[djur]

A popular introductory text like Learn You A Haskell doesn't introduce IO until chapter 9. It never gets beyond simple toy programs and the only further resource suggested (in the FAQ) is Real World Haskell.

RWH is well-written and covers some real-world tasks, but some of its examples are outdated enough that they don't even compile anymore (at least, I encountered that scenario a year ago or so) and Haskellers will frequently warn people that parts of it are out of date (see elsewhere in these comments).

I actually think one of the shortcomings of Haskell's approach to new developers is that it _is_ very much a general purpose programming language and sold as such. Other languages have extremely popular frameworks or applications which serve to attract newcomers. People teach Swift or Objective-C to write iOS apps, Java for Android apps, JavaScript to do web apps, Ruby to write web backends in Rails, C# to write games in Unity... hell, people learn Java to make Minecraft mods. The closest thing I can think of for Haskell is Xmonad, which doesn't exactly have mass appeal.

Someone else suggested "Write Yourself A Scheme" as a good practical introduction, and that in itself says a lot about who Haskell appeals to -- people who are interested in programming languages. The MLs and Haskell remind me of Brian Eno's line about how the first Velvet Underground album only sold 30,000 copies, but "everyone who bought one of those 30,000 copies started a band".