The Snap team is proud to announce the release of Snap 0.4.1, containing bugfixes and efficiency improvements. Here are the changes since 0.4.0:


  • The MonadCatchIO instance for the Snap monad was broken (this was bug #48 on the issue tracker), causing exceptions to leak outside of catch blocks. This is now fixed. Thanks to Bryan O’Sullivan for reporting this.

  • Fixed several space leaks in file upload support, one of which was fixed by a new release of enumerator. Thanks to John Millikin for fixing the space leak in Iteratee bind. CPS is hard!

  • Our code which generated “Set-Cookie” headers from the Cookie list stored in the Response object had the unfortunate side-effect of blowing away any “Set-Cookie” headers users put into the response by hand.

Efficiency improvements

Upcoming talk

Gregory Collins will be speaking at QCon London on Friday, March 11 about “High-performance web applications in Haskell”. The talk is not specifically about the Snap Framework — although Snap will be discussed — but instead will be about why Haskell is a great fit for high-performance web applications, with a nod to projects like Happstack, Warp, and Yesod.