anchor.diff:  ﻿namespace FSharpx.Books.DSLsInAction.Chapter8.Scala.Trading.SSI
   
   module AST =
  +    // Listing 8.8 The Semantic Model (AST) for the SSI DSL
  +
       type Market = string
       type Security = string
       type CustomerCode = string
  
positive.code:     open System
      open AST
  
      let ws = spaces1
      let str s = pstring s .>> ws
      let betweenStrings s1 s2 p = pstring s1 >>. p .>> pstring s2
      let inline const' x = fun _ -> x
  
negative.code:     let parseTradings str = 
          match run standingRules str with
          | Success(result, _, _)   -> result
          | Failure(errorMsg, _, _) -> failwithf "Failure: %s from \"%s\"" errorMsg str
  