patch applied (packages/base): Inline Data.Bits.rotate@Int, enables rotate to be constant folded

[Don Stewart]

Thu May  1 16:01:52 PDT 2008  Don Stewart <dons at galois.com>
  * Inline Data.Bits.rotate at Int, enables rotate to be constant folded
  
  All other Bits instances seem to inline well enough on their own
  to enable constant folding, e.g.
  
      sumU . mapU (`shift` 3) . replicateU 10000000 $ (7 :: Int)
  
  goes to:
  
      Main.$wfold =
        \ (ww_sOb :: Int#) (ww1_sOf :: Int#) ->
          case ww1_sOf of wild_XM {
            __DEFAULT -> Main.$wfold (+# ww_sOb 56) (+# wild_XM 1);
            10000000 -> ww_sOb
          }
  
  With this patch, rotate gets inlined and folded too,
  
      sumU . mapU (`rotate` 3) . replicateU 10000000 $ (7 :: Int)
  
  to:
  
    Main.$wfold =
      \ (ww_sO7 :: Int#) (ww1_sOb :: Int#) ->
        case ww1_sOb of wild_XM {
          __DEFAULT -> Main.$wfold (+# ww_sO7 56) (+# wild_XM 1);
          10000000 -> ww_sO7
  
  Whereas it was left as a call to $wrotate before.
      
  

    M ./Data/Bits.hs -1 +8

View patch online:
http://darcs.haskell.org/packages/base/_darcs/patches/20080501230152-cba2c-adb8ea1981dbc6427b2d85b054533517ffc3b4c3.gz