I am sorry, I fail to see a bug there which "cannot be detected by any test until running in production on real data when it is already too late". It's mainly problems with lazy IO which should be detected by unit tests using test data, right? The first answer is actually a nasty bug, but you should probably not deploy code which sends your test suite into an endless loop no matter in which language it is written. Yes, Haskell does not solve all programming problems, but I don't see anything which could not be found by testing here.

Unit test will not detect everything. You need real data under heavy load for Haskell. This is a _fact_.

Most of you here should stop writing BS about Haskell and how it is going to save the world.

> I never said that. Your argument was that this is specific to Haskell which is not.

It is specific to lazily evaluated languages, especially Haskell. To test Haskell program you will need a real environment under heavy load - maybe Google or Amazon could afford it. Tiny unit tests which are perfect for strictly evaluated languages won't detect these kid of bugs.

> Unit test will not detect everything.

I never said that. Your argument was that this is specific to Haskell which is not.

> You need real data under heavy load for Haskell.

How is this different from other languages?

> This is a _fact_.

Using "_" does not replace an actual argument ;)

> Most of you here should stop writing BS about Haskell and how it is going to save the world.

I fact, I wrote the opposite in the parent of your post.