#14163: Stack Overflow with ApplicativeDo -------------------------------------+------------------------------------- Reporter: lippling | Owner: simonmar Type: bug | Status: new Priority: high | Milestone: 8.2.2 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: ApplicativeDo Operating System: MacOS X | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by dfeuer): I have a pretty decent guess about the problem. We have {{{#!hs mkStmtTreeHeuristic :: [(ExprLStmt GhcRn, FreeVars)] -> ExprStmtTree mkStmtTreeHeuristic [one] = StmtTreeOne one mkStmtTreeHeuristic stmts = case segments stmts of [one] -> split one segs -> StmtTreeApplicative (map split segs) where split [one] = StmtTreeOne one split stmts = StmtTreeBind (mkStmtTreeHeuristic before) (mkStmtTreeHeuristic after) where (before, after) = splitSegment stmts }}} The `do` block in question can't actually be split at all (all the pattern matches are strict). So I ''think'' the trick is probably to make sure `before` is non-empty before producing `StmtTreeBind`. I'll give this a whirl. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14163#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler