Working with Parser Combinators: Listing 2.

Converting input into a PhoneNumber object.

public static Parser<string> fourNumberParser =
  Parse.Numeric.Then(first =>
    Parse.Numeric.Then(second =>
      Parse.Numeric.Then(third =>
        Parse.Numeric.Then(fourth =>
          Parse.Return("" + first.ToString() +
            second.ToString() + third.ToString() +
public static Parser<string> areaCodeParser =
  (from number in threeNumberParser
  select number).
  from lparens in Parse.Char('(')
  from number in threeNumberParser
  from rparens in Parse.Char(')')
  select number);
public static Parser<PhoneNumber> phoneParser =
  (from areaCode in areaCodeParser
  from _1 in Parse.WhiteSpace.Many().Text()
  from prefix in threeNumberParser
  from _2 in (Parse.WhiteSpace.Many().Text()).
  from line in fourNumberParser
  select new PhoneNumber() { AreaCode=areaCode, Prefix=prefix, Line=line});

About the Author

Ted Neward is a programming language, virtual machine, and enterprise-scale architect. He has written a dozen books and hundreds of articles on .NET, Java, enterprise systems, mobile development, and programming languages. He resides in the Pacific Northwest, and can be found on the Internet at,, @tedneward on Twitter, and blogs at

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