#11760: runST with lazy blackholing breaks referential transparency -------------------------------------+------------------------------------- Reporter: Yuras | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 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 NeilMitchell): It turns out the widely used zlib library suffers from exactly this issue, and can segfault when executed in parallel. See https://github.com/haskell/zlib/issues/7#issuecomment-253028108 for more details. It seems like adding {{{noDuplicate}}} to {{{runST}}} and adding {{{unsafeRunST}}} is a reasonable compromise. There may be a performance impact on {{{runST}}}, but having segfaults/value-changes should require typing something with the word {{{unsafe}}} in it at some point. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11760#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler