On: Monads and Macros

[maxiepoo]

Exactly, Haskell's "do" notation is essentially defined as a built-in macro, so if you ever want to use "do" notation in a language that doesn't have it built-in you will need to use macros. (Let-binding overloading is essentially do notation in case that's not clear)

[marcosdumay → maxiepoo]

Macros are way more powerful than binding, for both the best and the worst.

Yes, you can use macros to add do-notation to a language. But you can also use macros to add things like type checks and new conditional statements. You can't add those with do-notation.

[tromp → maxiepoo]

do is more syntactic sugar for >>= (monadic bind) than macro. E.g.

    do
      s <- readLine "Enter name:"
      putStr $ "Hello, " ++ s

reduces to

    readLine "Enter name:" >>= (\s -> putStr $ "Hello, " ++ s)

But I agree you can use macros to implement syntactic sugar.

[whateveracct → maxiepoo]

"do" is also no longer hard-coded. There are multiple language extensions that allow you to change what it desugars to, which is really cool.