Am 12.10.2011 23:24, schrieb Benedict Eastaugh:
Hi Alex,
since Daniel has done a nice job of actually answering your questions, I shall just note that I have a module similar to this available on Hackage as part of my hatt package, which generates truth tables for formulae in classical propositional logic.
http://hackage.haskell.org/package/hatt http://hackage.haskell.org/packages/archive/hatt/1.3.0/doc/html/Data-Logic-P...
Why do most people like duplicate or repeated code? Instead of data Expr = Variable String | Negation Expr | Conjunction Expr Expr | Disjunction Expr Expr | Conditional Expr Expr | Biconditional Expr Expr you are usually better served by: data Expr = Variable String | Negation Expr | Junct BinOp Expr Expr data BinOp = Conjunction | Disjunction | Conditional | Biconditional Cheers Christian
Benedict