Miss Dada  🏳️‍⚧️

@cartazio @ReinH I wanted to provide a point of extension, without having to know about every possible type of renderable.

@sgrif @cartazio you can do that without the type class. I’m not sure it’s worth it in this case. http://lukepalmer.wordpress.com/2010/01/24/haskell-antipattern-existential-typeclass/ …

@ReinH @cartazio I have seen that solution before, but it never felt like it was a great solution to me.

@sgrif @cartazio I’ve seen better haskellers than me choose the type class for similar situations so I wouldn’t worry about it.

@ReinH @cartazio I'm just too used to being able to have a list of an interface in Scala

@sgrif @cartazio … and other ways to structure the sequencing of effectual computation :)

@ReinH @cartazio https://gist.github.com/sgrif/b9ec575ead0ca1ce2686 … <-- Would love some other ways to structure this if you've got additional solutions.

@sgrif @cartazio classes become types, types become values: type Renderable = IO () rectangle w h = undefined renderEverything = sequence_