tibbe committed f80493b

Document optimizations in ensure

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 ensure :: Int -> Parser B.ByteString
 ensure !n = T.Parser $ \i0 a0 m0 kf ks ->
     if B.length (unI i0) >= n
+    -- Inline the success continuation to avoid creating a closure in
+    -- the common case of enough data in the buffer:
     then inline ks i0 a0 m0 (unI i0)
+    -- The uncommon case is kept out-of-line to reduce code size:
     else ensure' n i0 a0 m0 kf ks
+-- Non-recursive so the bounds check can be inlined:
 {-# INLINE ensure #-}
 -- | Ask for input.  If we receive any, pass it to a success