Haskell Language Cost Centers


Cost centers are annotations on a Haskell program which can be added automatically by the GHC compiler -- using -fprot-auto -- or by a programmer using {-# SCC "name" #-} <expression>, where "name" is any name you wish and <expression> is any valid Haskell expression:

-- Main.hs
main :: IO ()
main = do let l = [1..9999999]
          print $ {-# SCC "print_list" #-} (length l)

Compiling with -fprof and running with +RTS -p e.g. ghc -prof -rtsopts Main.hs && ./Main.hs +RTS -p would produce Main.prof once the program's exited.