#14594: 2 modules / 2500LOC takes nearly 3 minutes to build -------------------------------------+------------------------------------- Reporter: schyler | Owner: dfeuer Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: 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: | -------------------------------------+------------------------------------- Comment (by dfeuer): I tried generating a bunch of modules with derived data instances. A module with 29 single-field instances desugars to 5201 terms, 13488 types, 145 coercions. This is a similar number of terms as `Data.Set.Internal`, but about twice as many types. Core tidy is 11,705 terms, 21,960 types, and 1,479 coercions. GHC allocates 2,222,336,112 bytes compiling this compared to 1,663,610,072 for compiling `Data.Set.Internal`. I also noticed that there's actually a strong non-linearity at the low end: types with small umbers of fields have high incremental costs. For 50 definitions, using 0,1,2,3, and 4 fields each, I get 2.49, 3.85, 4.92, 5.51 and 5.66 GB of GHC allocation, respectively. I need to explore this a bit more. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14594#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler