anchor.diff:  module FSharpLex.Compile
   
   open System.Diagnostics
  +open LanguagePrimitives
  +open ExtCore
  +open ExtCore.Collections
   open SpecializedCollections
  -open LanguagePrimitives
   open Graph
   open Regex
   open Ast
  
positive.code:     //
      // OPTIMIZE : Modify this function to use a LazyList to hold the errors
      // instead of an F# list to avoid the list concatenation overhead.
      let rec validateAndSimplify pattern cont =
          match pattern with
          | Pattern.Epsilon ->
  
negative.code:                     |||> Array.fold2 (fun map (_, ruleId) compiledRule ->
                          Map.add ruleId compiledRule map); }
          else
              Choice2Of2 <| Array.concat compilationErrors
  
  