Hacker News Reader

Comment by l_dopa | Hacker News Reader

> A lot of Harper's comments ( and many PL theorists ) seem to completely casually gloss over the gritty compiler engineering as if it's just beneath them, and that guys like SPJ and Simon Marlow are just wasting their time working on faster runtime systems and optimizations when he thinks they should be working on foundational "Holy Trinity" problems.

That's a tempting view to take regarding theory vs. practice but I don't think it holds up when you consider Harper's whole body of work and the substance of his criticisms of Haskell: He has published extensively on ML implementation and, as far as I know, has offered criticism of (GHC) Haskell's type system where it is unsound, never the (really cool) work being done on the RTS.

View on HN

I've read his papers and I own his books, so I'm not entirely unfamiliar with his contributions to the field. But I also find his criticism of Haskell to be at best detached from reality and a "holistic" view of the programming profession as a union of theory, engineering, and community. Especially when he's arguing for the use of pure academic languages like Agda or antiquated ML-dialects that haven't seen active development in 15 years, over a productive language like Haskell. In an industry where regression languages like Go and Javascript are seeing wide adoption, I think his grandstanding does a lot more harm than good.

That makes sense. If you view Haskell as a research platform, pointing out ugly corners of the type system is entirely appropriate and even helpful for people working on GHC. From the outside, for those of us that would like to see these ideas gain greater adoption, it can be frustrating or even seem petty to focus on them.

It is helpful and appropriate to point out bugs, and his comments did help fix the Typeable exception problem in GHC 7.8. But he doesn't go through the usual tracker and mailing list to report these things. He goes off and writes these angry blog posts and extrapolates small defects to justify sensationalist claims about the whole language. On one hand you have a respected PL researcher, on another you have a guy who is like the axe-grinding "Zed Shaw" of functional languages.

Yes, this is what compelled me to comment in the first place: based on what I've read of his blog, that comparison (and his reputation in general) seems completely unjustified. There's a world of difference between this kind of spirited but productive debate and content-free holy wars between roughly identical languages that get the spotlight in the "mainstream" tech blog circuit.

In fact, his post on exceptions in Haskell and his criticism of monadic IO led me to work on some alternatives (algebraic effects) which, oddly enough, helped me understand Haskell's approach at a deeper level. I wouldn't have known about the issue if it was only on the bug tracker.

Reply on news.ycombinator.com