The Yesod package includes an executable that uses some Template Haskell. Due to the way GHC works, there are a few hoops to jump through to get this to compile when profiling is enabled. To get around the issue, try installing Yesod with:
cabal install yesod --disable-executable-profiling
This practice is already common in the web development world, with Sass and Coffeescript. Here's a number of reasons why we do this in Yesod:
Make sure that all your Handler files are listed in the cabal file, in the
Please see PostgreSQL-UTCTime for more information.