Re: [Haskell-cafe] Concept for "equal but unknown"

Hello, Do you mean something like variable unification in Prolog or Oz? Maybe something like this could help you: https://hackage.haskell.org/package/monad-unify-0.2.2/docs/Control-Monad-Uni... or https://hackage.haskell.org/package/unification-fd Disclaimer: I've never used either of those packages. Best regards, Marcin Mrotek