What about the Identity monad? Does that "force sequencing"? What "sequencing relationship" does it create?
If you are convinced that the Identity monad does "force sequencing" then you are also convinced that lazy evaluation "forces sequencing" (because the Identity monad is just lazy evaluation). That would be a fairly controversion conviction. If you are not convinced that the Identity monad "forces sequencing" then can you explain in more detail the meaning of your claim "What a Monad does is to force sequencing by creating a data dependency.".
It's in the signature. `b` has a causal dependency on `a` because `a` is on the left hand side of the arrow and `b` is on the right hand side of the arrow. That's it. Functional programming 101. There's no way around this.
The operational semantics and details of thunks are not relevant here. Tricks with `undefined` are not relevant here. This is just the meaning of the arrow type.
Because the values have extra "stuff" surrounding them. That's why it's `m a` and not just `a`: the `m` holds the invisible context that enriches the `a`.
Although your example is exactly what's happening in the identity monad, because there is no extra stuff.
Monads have been called "executable semicolons", because you can define a function to be executed each time the program passes from one statement to the next.
If you are convinced that the Identity monad does "force sequencing" then you are also convinced that lazy evaluation "forces sequencing" (because the Identity monad is just lazy evaluation). That would be a fairly controversion conviction. If you are not convinced that the Identity monad "forces sequencing" then can you explain in more detail the meaning of your claim "What a Monad does is to force sequencing by creating a data dependency.".