I n the functional-programming world, traditional design patterns generally manifest in one of three ways:

  • The pattern is absorbed by the language.
  • The pattern solution still exists in the functional paradigm, but the implementation details
  • The solution is implemented using capabilities other languages or paradigms lack. (For example, many solutions that use metaprogramming are clean and elegant — and they're not
    possible in Java.)

Neal Ford

http://www.ibm.com/developerworks/java/library/j-ft10/j-ft10-pdf.pdf