Comment by SparklingCotton

No it simply does not, because the language forces you to write pure functions. The type system invites you to express invariants.

There are very fundamental connections between strong typing, program verification, and proofs.

http://en.wikipedia.org/wiki/Curry-Howard_correspondence

Thus, the argument that Haskell probably has the same, is simply false.

There are large web platforms in Haskell. Yesod is probably the largest eco-system. It is clearly not as well used as RoR, but anyone can dig through large amounts of code to try to find these bugs.

What Haskell has that everyone else has are bugs/misunderstandings in how protocols are implemented. Sometimes there can be fundamental bugs in the run-time-system. However, large classes of bugs are fundamentally less likely to appear than in less safe languages.