OO vs FP

OOvsFP.md

Today I was having a discussion on twitter, and after re-reading my timeline and seeing this tweet, I decided to blog about it.

This is the gist of it

	Encapsulation	Abstraction
OO	Required	To be avoided
FP	To be avoided	Required

A small explanation

Encapsulation vs abstraction

Demis' tweet explains it perfectly:

@ashic @ToJans @abdullin @NeilRobbins information hiding is encapsulation, creating layers is abstraction

— Demis Bellot (@demisbellot) 24 juni 2014

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OO thrives on encapsulation:

• Behaviour is captured in systems, hiding the concrete types and data.
• System interactions use purpose-built integration points/contracts (i.e. public and/or interfaces).
• Composition happens using explicit contracts, and usually requires an integration system/- class.

FP thrives on abstraction

• Behaviour is captured in functions that have a precise notion of the type/parameter's meaning.
• System design is driven by the this meaning and creating new types/meanings.
• As functions have a precise notion on this meaning, one can easily compose behaviour by chaining functions.