I use it to solve problems. I have a database with millions of unstructured JSON documents. I wrote a tool in Haskell to scan the database, parse the unstructured documents and collect the results. It displays the ratio of successful parses and the top N parse errors with a sample to add to my test suite.

Once I can parse 100% of the database I can use another library I'm working on that can migrate between data structures while preserving information and provenance.

Then I can safely migrate millions of lines of unstructured documents with dozens of weird corner cases to a collection of documents with consistent structure and few corner cases.

Sure I could do this in pretty much any language on the market but I've put relatively little effort into this and am nearly done. Programming in Haskell has a good power-to-weight ratio.

I don't really have anything to complain about tools-wise. It's all standard fare or better than most other language ecosystems as far as I'm concerned.