1 files changed, 13 insertions, 7 deletions

diff --git a/bittorrent/src/Network/BitTorrent/Exchange/Bitfield.hs b/bittorrent/src/Network/BitTorrent/Exchange/Bitfield.hs
index 7bae3475..1be9f970 100644
--- a/bittorrent/src/Network/BitTorrent/Exchange/Bitfield.hs
+++ b/bittorrent/src/Network/BitTorrent/Exchange/Bitfield.hs
@@ -9,7 +9,7 @@
 --   bitfields. Bitfields are used to keep track indices of complete
 --   pieces either this peer have or remote peer have.
 --
---   There are also commonly used piece seletion algorithms
+--   There are also commonly used piece selection algorithms
 --   which used to find out which one next piece to download.
 --   Selectors considered to be used in the following order:
 --
@@ -108,12 +108,17 @@ import Data.Torrent
 
 -- TODO cache some operations
 
--- | Bitfields are represented just as integer sets but with
--- restriction: the each set should be within given interval (or
--- subset of the specified interval). Size is used to specify
--- interval, so bitfield of size 10 might contain only indices in
--- interval [0..9].
+-- | Bitfields are represented just as integer sets but with a restriction:
+-- each integer in the set should be within the given interval.  The greatest
+-- lower bound of the interval must be zero, so intervals may be specified by
+-- providing a maximum set size.  For example, a bitfield of size 10 might
+-- contain only indices in interval [0..9].
 --
+-- By convention, we use the following aliases for Int:
+--
+--   [ PieceIx ] an Int member of the Bitfield.
+--
+--   [ PieceCount ] maximum set size for a Bitfield.
 data Bitfield = Bitfield {
     bfSize :: !PieceCount
   , bfSet  :: !IntSet
@@ -257,6 +262,7 @@ rarest xs
     = Just $ fst $ V.ifoldr' minIx (0, freqMap V.! 0) freqMap
   where
     freqMap = frequencies xs
+    {-# NOINLINE freqMap #-}
 
     minIx ::  PieceIx -> Frequency
           -> (PieceIx,   Frequency)
@@ -393,7 +399,7 @@ rarestFirst h a xs = rarest (map (intersection want) xs)
 randomFirst :: Selector
 randomFirst = do
 --  randomIO
-  error "randomFirst"
+  error "TODO: randomFirst"
 
 endGame :: Selector
 endGame = strictLast