twhitehead:
Consider the following code
data Data = Data { unData :: !Int }
func :: Data -> Int func x = case unData x of 1 -> 2 _ -> 0
Compiling with GHC 6.8.2 gives the following stg code
Main.func = \r [x_slg] case x_slg of tpl_slx { Main.Data ipv_slj -> case ipv_slj of wild_sly { GHC.Base.I# ds_slm -> case ds_slm of ds1_slz { __DEFAULT -> Main.lvl1; 1 -> Main.lvl; }; }; };
Note that using -funbox-strict-fields helps, A.func :: A.Data -> Int A.func = \ (x_afx :: A.Data) -> case x_afx of tpl_B2 { A.Data rb_B4 -> case rb_B4 of ds_Xg7 { __DEFAULT -> A.lvl1 1 -> A.lvl } } No I#. I'd expect if 'func' was inlined, for the return to be unboxed as well. -- Don