I was able to reproduce this issue using lists instead of vector
#13429: Optimizer produces Core with an infinite <<loop>> -------------------------------------+------------------------------------- Reporter: lehins | Owner: (none) Type: bug | Status: merge Priority: normal | Milestone: 7.10.4 Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by dfeuer): Replying to [comment:2 lehins]: package, confirming that it is indeed a bug in ghc. Could you attach that reproduction here? I suspect this might be worth investigating a bit more, despite the pain, to make sure that the underlying problem was actually fixed and not just buried. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13429#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler