On Wed, Jul 29, 2015 at 05:43:23PM +0200, Merijn Verstraaten wrote:
newtype Expr a = Expr { unExpr :: Free (ExprF Expr) a } deriving (Functor,Applicative,Monad,Foldable,Traversable)
data ExprF f a = App (f a) (f a) | Lam Type (Scope () f a) | TmTrue | TmFalse | If (f a) (f a) (f a) deriving (Eq,Ord,Show,Read,Functor,Foldable,Traversable)
Now, for an AST to be useful, it has to be annotated with things like source location, type info, etc. So I started looking into how to accomplish this in a way where it's easy to add/modify annotations on any node of the AST.
If you want *some* subterms to be annotated, can you just add another constructor to ExprF? | Annotation annotationType (f a) Or if you want *every* subterm annotated then how about newtype Expr f a = Expr { unExpr :: Free (ExprF (Compose f Expr)) a }