That's because it's taken from a library that deals with graphs[1]. I had to look it up, because I had no idea what it does either and I know Haskell. Here's a

That's because it's taken from a library that deals with graphs[1]. I had to look it up, because I had no idea what it does either and I know Haskell. Here's a better example of what he meant in Elm, a language that looks a lot like Haskell: https://github.com/bryanjenningz/25-elm-examples/blob/master/18-editable-todos.elm https://github.com/bryanjenningz/25-elm-examples/blob/master... [1]: http://hackage.haskell.org/package/fgl-5.7.0.1/docs/Data-Graph-Inductive-Graph.html http://hackage.haskell.org/package/fgl-5.7.0.1/docs/Data-Gra...