[black_knight]

Your description sounds about right!

I learned to understand it [0][1] as a way of creating free monads by wishing for a list of effects at the type level. Then later you worry about how to implement the effects. Solves the same problem as monad transformers, but without commit to an order up front (and without all the boilerplate of mtl).

My idea is that you should be able to create and pass around typed capabilities for effects, and then transparently get them “effectuated at their place of creation”.

[0] : http://okmij.org/ftp/Haskell/extensible/more.pdf

[1] : https://hackage.haskell.org/package/freer-simple

[tome]

Have you seen my effect system Bluefin? It sounds like exactly what you're describing:

https://hackage-content.haskell.org/package/bluefin-0.0.16.0...

Happy to answer any questions about it, either here, or if you open an issue: https://github.com/tomjaguarpaw/bluefin/issues/new

[black_knight]

Nice! This looks very interesting. Will for sure check it out.