#13615: Nondeterminism in ‘pure’ function w/ parallel evaluation & memo combinators -------------------------------------+------------------------------------- Reporter: pacak | Owner: bgamari Type: bug | Status: new Priority: highest | Milestone: 8.2.1 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 dfeuer): I've written a [https://github.com/treeowl/unordered-containers/tree /super-safe seriously legitimate modification] of `Data.HashMap.Strict.fromListWith` that Ben indicates still demonstrates the problem. This version uses a separate type of mutable hashmap that holds `MArray`s. When it's done, it traverses the tree and (unsafely) freezes all the arrays. Unless I've goofed up, there should be no doubt that this version should work correctly. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13615#comment:37 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler