Lightning - Monads you already use (without knowing it)

The lightning talk version of this talk.

Transcript

1. Monads you’ve already put in prod Tejas Dinkar Nilenso Software
2. about.me • Hi, I’m Tejas • Nilenso: Partner • twitter: tdinkar • github: gja
3. If you think you understand Monads, you don't understand Monads.
4. This talk is inaccurate and will make a mathematician cry
5. Monads • Programmable Semicolons • Used to hide plumbing away from you • Monads are just monoids in the category of endofunctors
7. Values Value
8. Monads Value Box
9. Monads • Monads define two functions • return takes a value and puts it in a box • bind takes a box & function, and returns a box with f(value)
10. Some math (√4) + 5
11. Some math (√4) + 5 3 or 7!
12. Value 4
13. Monad [4]
14. return def m_return(x) [x] end # m_r(4) => [4]
15. Square Root fn def sqrt(x) s = Math.sqrt(x) [s, -s] end # sqrt(4) => [2, -2]
16. Bind Function x = m_return(4) y = ?????(x) { |p| sqrt(p) } # I want [-2, 2]
17. Bind Function x = m_return(4) y = x.flat_map {|p| sqrt(p) } # y => [2, -2]
18. Increment Fn def inc_5(x) [x + 5] end # inc_5(1) => [6]
19. Putting it together m_return(4). flat_map {|p| sqrt(p)}. flat_map {|p| inc_5(p)} # => [3, 7]
20. You have invented the List Monad, used to model non-determinism Congrats