#7994: Make foldl into a good consumer -------------------------------------+------------------------------------ Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by nomeata): Yesterday it looked as if this has magically improved, but at least with the example from the ticket, put into self-contained as follows: {{{#!haskell module Foo( foo ) where import Data.Complex import Prelude hiding (sum, foldl) foldl k z xs = foldr (\v fn z -> fn (k z v)) id xs z {-# INLINE foldl #-} sum = foldl (+) 0 {-# INLINE sum #-} foo x = sum [f n | n <- [1 .. x]] f :: Int -> Complex Double {-# NOINLINE f #-} f n = mkPolar 1 ((2*pi)/fromIntegral n) ^ n }}} I still get bad code: {{{ Foo.$wfoo :: GHC.Prim.Int# -> Data.Complex.Complex GHC.Types.Double [GblId, Arity=1, Str=DmdType <L,U>, Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=1, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [0] 225 0}] Foo.$wfoo = \ (ww_s1nN :: GHC.Prim.Int#) -> case GHC.Prim.tagToEnum# @ GHC.Types.Bool (GHC.Prim.># 1 ww_s1nN) of _ [Occ=Dead] { GHC.Types.False -> letrec { go_a1k0 [Occ=LoopBreaker] :: GHC.Prim.Int# -> Data.Complex.Complex GHC.Types.Double -> Data.Complex.Complex GHC.Types.Double [LclId, Arity=1, Str=DmdType <L,U>] go_a1k0 = \ (x_a1k1 :: GHC.Prim.Int#) -> let { v_ayO [Dmd=<L,U(U(U),U(U))>] :: Data.Complex.Complex GHC.Types.Double [LclId, Str=DmdType] v_ayO = Foo.f (GHC.Types.I# x_a1k1) } in let { ds_dWw [Dmd=<L,C(U)>] :: Data.Complex.Complex GHC.Types.Double -> Data.Complex.Complex GHC.Types.Double [LclId, Str=DmdType] ds_dWw = case GHC.Prim.tagToEnum# @ GHC.Types.Bool (GHC.Prim.==# x_a1k1 ww_s1nN) of _ [Occ=Dead] { GHC.Types.False -> go_a1k0 (GHC.Prim.+# x_a1k1 1); GHC.Types.True -> GHC.Base.id @ (Data.Complex.Complex GHC.Types.Double) } } in \ (z_ayQ :: Data.Complex.Complex GHC.Types.Double) -> ds_dWw (Data.Complex.$fFloatingComplex_$s$c+ z_ayQ v_ayO); } in go_a1k0 1 Foo.foo1; GHC.Types.True -> Foo.foo1 } }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7994#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler