The profiles sometimes charges to the wrong account. In this example:
foo :: (() -> () -> [()] -> [()]) -> () -> [()] -> [()] foo k = \_ xs -> concatMap ($ [head xs]) [bar] where bar = let k' = k undefined undefined in \xs -> let k'' = [k' xs] in (() : (foldr1 (>>) k'')) k = foo (\_ -> k) --k a = foo (\_ -> k) a r = k undefined  !! 4000 main = print r
almost all of the time, allocations, and heap retention are charged to k. However, if you use the commented definition of k, the changes switch to foo, as expected. This can be tested by running
ghc --make -prof -auto-all Logic.hs && ./a.out +RTS -hc && hp2ps -c a.out.hp
and watching the pretty graph change.
This is using ghc 6.4.1 from Debian unstable. More background at http://haskell.org/pipermail/haskell-cafe/2006-February/014139.html