composable-functional-javascript
Semigroup: datastructure that has .concat method Monoid: Semigroup that has a neutral element for concat method
14. Functors
- Any type with map method and follow those 2 laws below:
- fx.map(f).map(g) === fx.map(g(f(x)))
- fx.map(id) === id(fx)
15. Lift into a Pointed Functor with of
- Use of to create a Functor instead of using complex contructor so we can map right away, do calculation
16. You've been using Monads
- Any type with of and chain (flatMap, bind, >>==) method: Box, Either, Task, List
const join = m => m.chain(x => x);
- Law 1 join(m.map(join)) === join(join(m))
- Law 2 join(Box.of(m)) === join(m.map(Box.of))
17. Build curried functions
- Preloading data into a function
- How to build: instead of function that take multi parameters, create a function that return a function that return a function and so on. Data will come last in the chain so we can build up know value first
18. Applicative Functors for multiple arguments
- Box of a function we want to apply that funciton to another Box of a value
- F(x).map(f) === F(f).ap(F(x))
23. Maintaining structure whilst asyncing
- We take our Promise.all() analogy further by using traversable on a Map(). Then we use two traversals in the same workflow.
24. Principled type conversions with Natural Transformations
- We learn what a natural transformation is and see the laws it must obey. We will see how a natural transformation must uphold the law of
nt(x).map(f) == nt(x.map(f)).
25. Apply Natural Transformations in everyday work
- We see three varied examples of where natural transformations come in handy.
26. Isomorphisms and round trip data transformations
- We formally define isomorphisms, make a few, then use them to accomplish normal programming tasks
27. Build a data flow for a real world app
- We form a plan to find the common ground between two artists from the spotify api. Then we sketch out a data flow to ensure we have what we need, when we need it.
28. Find the intersection of sets with Semigroups
- We use semigroups to find the intersection of sets, then expand that to work on as many artists as we'd like. Finally, we use foldable to show a pair of intersection and sum to shed more light on the final result set.