Help with use of functional dependencies?

Don't use fundeps, they are too much pain. Use associated types.

Don't use fundeps, they are too much pain. Use associated types. Class (Eq (Vertex g), Eq (Edge g)) => Graph g where type Edge g :: * type Vertex g :: * edges :: g -> Edge g src :: g -> Edge g -> Vertex g dst :: g -> Edge g -> Vertex g vertices :: g -> Vertex g vertices g = nub $ map (src g) (edges g) ++ map (dst g) (edges g) class Graph g => Subgraph g where extVertices :: g -> Edge g data Subgraph1 g where Subgraph1 :: Graph g => g -> Edge g -> Subgraph1 g instance Graph g => Graph (Subgraph1 g) where type Edge (Subgraph1 g) = Edge g type Vertex (Subgraph1 g) = Vertex g vertices (Subgraph1 g _) = vertices g edges (Subgraph1 g _) = edges g src (Subgraph1 g _) = src g dst (Subgraph1 g _) = dst g This looks somewhat more readable.

Edge g is the type of g's edges, etc. Note that I translated your code mechanically, without understanding what Subgraph1 does. Why do you need a GADT here, and what the second argument of the data constructor means? It is not used anywhere.

Nice, that looks beautiful! I read about these but haven't used them yet. The GADT was used to say that only types g which were graphs could be used to construct Subgraph1.

– gatoatigrado Jul 23 at 17:18.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.