#14254: The Binary instance for TypeRep smells a bit expensive -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Typeable Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by dfeuer: Old description:
In particular, `get` uses `getSomeTypeRep`. `getSomeTypeRep`, in turn, calls `typeRepKind` through its recursion. But `typeRepKind` is itself recursive, fully inspecting the spine of its argument. That smells quadratic to me. The solution, I believe, is to change the type of `getSomeTypeRep` to `BinHandle -> IO (SomeTypeRep, TypeRep Type)`.
New description: In particular, `get` uses `getSomeTypeRep`. `getSomeTypeRep`, in turn, calls `typeRepKind` through its recursion. But `typeRepKind` is itself recursive, fully inspecting the spine of its argument. That smells quadratic to me. The solution, I believe, is to change the type of `getSomeTypeRep` to `BinHandle -> IO (SomeTypeRep, SomeTypeRep)`. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14254#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler