Why doesn’t monad take `(M a -> M b)`?

All apologies — I’m still very much on the outside of Haskell looking in.

Why does a monad use “return” or “unit” rather than “lift”?

This is partly genuine curiosity, and partly a check on my understanding. I’m probably missing the point.

Why does a monad use “return” or “unit” rather than “lift”?

This is partly genuine curiosity, and partly a check on my understanding. I’m probably missing the point.

Picking a card from a shuffled deck

I’m pretty new to Haskell although I did some ML many moons ago.

Picking a card from a shuffled deck

I’m pretty new to Haskell although I did some ML many moons ago.

Picking a card from a shuffled deck

I’m pretty new to Haskell although I did some ML many moons ago.

Picking a card from a shuffled deck

I’m pretty new to Haskell although I did some ML many moons ago.

Picking a card from a shuffled deck

I’m pretty new to Haskell although I did some ML many moons ago.

Picking a card from a shuffled deck

I’m pretty new to Haskell although I did some ML many moons ago.

What is the “Free Monad + Interpreter” pattern?

I’ve seen people talking about Free Monad with Interpreter, particularly in the context of data-access. What is this pattern? When might I want to use it? How does it work, and how would I implement it?