anchor.diff:  module ByteComparer = 
       // this code is very non-F#-ish.  but it's much faster.
   
  -    let Compare (x:byte[], y:byte[]) =
  +    let Compare (x:byte[]) (y:byte[]) =
           let xlen = x.Length
           let ylen = y.Length
           let len = if xlen<ylen then xlen else ylen
  
positive.code:         // cannot be captured by a closure.
          let cur = ref -1
          let keys:byte[][] = (Array.ofSeq pairs.Keys)
          let sortfunc x y = ByteComparer.Compare(x, y)
          Array.sortInPlaceWith sortfunc keys
  
          let rec search k min max sop le ge = 
  
negative.code:                 i <- i + 1
          if i>len then result else (xlen - ylen)
  
      let CompareWithin (x:byte[]) off xlen (y:byte[]) =
          let ylen = y.Length
          let len = if xlen<ylen then xlen else ylen
          let mutable i = 0
  