3 FP Concepts: Recursion, List Comprehensions and Monads
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The document discusses three functional programming concepts: recursion, list comprehensions, and monads. Recursion is defined as a function that calls itself, allowing the definition of infinite sets through finite statements. List comprehensions provide a syntactic construct for expressing operations on lists, inspired by set comprehensions in mathematics. Monads deal with side effects in a functional way by encapsulating control flow and state propagation, allowing pure functional programming to interact with input/output through monadic types and functions that satisfy certain laws.
![Monads
Deal with side-effects in a functional way
Mathematical construct
Without monads PURE FP would be nuts
Functional able todo IO
Good to Control tracking of things
Similar to AOP Interceptors
Function Composition: LINQ, Unix Pipes
You can build environments that support exactly
the features that you want (Scala Option[A])
Encapsulating two things:
control flow (Maybe, Error, List, Continuation, parser monads)
state propagation (State, Reader, Writer, IO)](https://image.slidesharecdn.com/3fpconcepts-120331082157-phpapp02/85/3-FP-Concepts-Recursion-List-Comprehensions-and-Monads-14-320.jpg)
![Monads have laws…
its not just type/classes
Make possible assumptions about the
type/class and his behavior.
1. Left Identity (apply function to value)
return x >>= f (the same as) f x
sample: return 3 >>= (x -> Just (x+100000))
2. Right Identity (value to feed return)
m >>= return (the same as) m
sample: [1,2,3,4] >>= (x -> return x)
3. Associativity (no matter how nested chain)
(m >>= f) >>= g (the same as) m >>= (x -> f x >>= g)
sample: return (0,0) >>= landRight 2 >>= landLeft 2 >>= landRight 2](https://image.slidesharecdn.com/3fpconcepts-120331082157-phpapp02/85/3-FP-Concepts-Recursion-List-Comprehensions-and-Monads-16-320.jpg)
3 FP Concepts: Recursion, List Comprehensions and Monads
- 1. 3 FP Concepts Recursion, List comprehensions and Monads @diego_pacheco about.me/diegopacheco
- 2. 3 FP Concepts Recursion List Comprehensions Monads
- 3. Recursion
- 4. Recursion Function defined inside a function Function calling it-self Defining an infinite set of objects by a finite statement (Recursion Power by Wikipedia) Same behavior as loop, for, while, etc…
- 5. Recursion
- 7. List Comprehensions Syntactic construct based on lists Inspired by math: set comprehensions Expressions on lists, powerful stuff!
- 9. Monads
- 10. Monads => NO State on a world FULL of State, Looks nonsense!? WTF?
- 11. FP/Haskell are against state? Hell No! It’s all about discipline state…
- 12. How to Deal with state without global shared state variables ?
- 13. Workaround => Truck Food as Monad !!! (Abstraction)
- 14. Monads Deal with side-effects in a functional way Mathematical construct Without monads PURE FP would be nuts Functional able todo IO Good to Control tracking of things Similar to AOP Interceptors Function Composition: LINQ, Unix Pipes You can build environments that support exactly the features that you want (Scala Option[A]) Encapsulating two things: control flow (Maybe, Error, List, Continuation, parser monads) state propagation (State, Reader, Writer, IO)
- 15. Monads as types/class (>>=), OOP!?
- 16. Monads have laws… its not just type/classes Make possible assumptions about the type/class and his behavior. 1. Left Identity (apply function to value) return x >>= f (the same as) f x sample: return 3 >>= (x -> Just (x+100000)) 2. Right Identity (value to feed return) m >>= return (the same as) m sample: [1,2,3,4] >>= (x -> return x) 3. Associativity (no matter how nested chain) (m >>= f) >>= g (the same as) m >>= (x -> f x >>= g) sample: return (0,0) >>= landRight 2 >>= landLeft 2 >>= landRight 2
- 17. Monads >>= (bind)
- 18. Monads
- 20. 3 FP Concepts Thank You! Obrigado! Higher Order Functions, Lambda and Currying @diego_pacheco about.me/diegopacheco