Also the improvements of freeing you from inherita...

# arrow

[raulraja]

Also the improvements of freeing you from inheritance all together if you choose to not use sub typing and encouraging horizontal composition and separation of data and behaviors.

[Imran/Malic]

what is horizontal composition and sub typing?

[raulraja]

Horizontal composing without inheritance that is separating behaviors from data

[raulraja]

Vertical sub type based is what OOP frequently does which is extending classes to provide new behaviors

[raulraja]

Inheritance couples the data type to the behaviors tightly

[raulraja]

Same old 'has a' vs 'is a'

[raulraja]

FP leans more toward types can support behaviors but these behaviors are not necessarily part of the type hierarchy

[raulraja]

Interface and class that extends it is a subtype relationship

[raulraja]

But saying that class A supports behavior B expressed on an interface does not really require we.sruff the behaviors inside the data type

[raulraja]

They can be provided by an extension

[raulraja]

Or delegated by a bridge object or set of functions that provide the behavior

[raulraja]

FP favors this style of composition where the behavior part is pure functions and the data part is immutable data models

[raulraja]

And with that separation you can model anything including behaviors for types you have no control over what they extend

[raulraja]

Also this makes the point of why in FP hierarchies are.closed and not open

[raulraja]

They don't need to

[raulraja]

You can add any behaviors you want to FP to third.party data types even when they are closed through type classes and extensions

[Imran/Malic]

Is Delegation > Extension with @extension https://kotlinlang.slack.com/archives/C5UPMM0A0/p1555284425041800?thread_ts=1555241782.037300&cid=C5UPMM0A0

[Imran/Malic]

To put it simpler. What is more favoured in which use case. So far I always use Delegation to compose

[thanerian]

An example of horizontal composition is the usage of Comparator vs vertical composition with Comparable

[raulraja]

@thanerian exactly

[raulraja]

Comparator would work out of the box with Keep 87

[raulraja]

as a type class