Hi, I'm a Haskell newbie, but not new to programming, and I have a question regarding style (I think). I'm writing a parser for OMG's OCL, and have two ways of defining the AST model of a constraint. Each constraint in OCL has the following 4 characteristics: 1. name :: Maybe String 2. context :: UmlElement 3. expr :: OclExpression 4. type :: OclConstraintType Now, having come from an O-O background, this looks right; however, in an FPL, it may not be. OclConstraintType is essentially an enumeration of the values: Invariant | Precondition | Postcondition | InitialValue | Derivation | Body The question is this: is it better to create a single type as above with a 'type' attribute, or would it be better to use the types as separate constructors of a Constraint, each constructor taking the same attributes? I'm looking to avoid any pitfalls that could occur with either decision, and at this point I don't know the benefits of doing it one way vs. the other. BTW, I am using UUST Parser Combinator AG for the parser definition, in case that makes a difference. Thanks! --doug