do notation

[JasonShin]

Based on the Monad implementation, we should be able to explain Haskell's do notation, potentially creating an emulation of it as well.

Take a look at an existing do notation crate https://github.com/TeXitoi/rust-mdo for an inspiration.

References:

• https://en.wikibooks.org/wiki/Haskell/do_notation
• https://docs.scala-lang.org/tour/for-comprehensions.html
• http://learnyouahaskell.com/a-fistful-of-monads

[Boscop]

Yes, please impl Monad for more types and provide a do-notation like rust-mdo :) I'm really looking forward to this..