title: F# parsing Abstract Syntax Trees
body: <p>What is the best way to use F# to parse an AST to build an interpreter? There are plenty of F# examples for trivial syntax (basic arithmatical operations) but I can't seem to find anything for languages with much larger ranges of features.</p>
  
  <p>Discriminated unions look to be incrediably useful but how would you go about constructing one with large number of options? Is it better to define the types (say addition, subtraction, conditionals, control flow) elsewhere and just bring them together as predefined types in the union?</p>
  
  <p>Or have I missed some far more effective means of writing interpreters? Is having an eval function for each type more effective, or perhaps using monads?</p>
  
  <p>Thanks in advance</p>