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Functional Architecture

Brian Lonsdorf

@drboolean

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https://bit.ly/2Xq8CU4

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Goal?

  • Modular
  • Extendable
  • Performant
  • Maintainable
  • Readable
  • etc

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populateContainer

makeItemActive

renderPattern

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expandZipCode() {}

getLatLong() {}

getPolygon() {}

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save() {}

find() {}

destroy(){}

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fullName() {}

averageScore() {}

friends() {}

lastLogin() {}

toString() {}

getCountry() {}

getState() {}

getNumber() {}

getStreet() {}

dedupe() {}

findMinimum() {}

intersection() {}

validate() {}

isPresent(){}

isUnique()

inEnum() {}

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expandZipCode() {}

getLatLong() {}

getPolygon() {}

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save() {}

find() {}

destroy(){}

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fullName() {}

averageScore() {}

friends() {}

lastLogin() {}

toString() {}

getCountry() {}

getState() {}

getNumber() {}

getStreet() {}

dedupe() {}

findMinimum() {}

intersection() {}

validate() {}

isPresent(){}

isUnique()

inEnum() {}

User

Address

Validations

Utils

Repo

Geolocate

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Address

User

Preferences

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Metaphors?

  • Know about context and domain
  • Mixed metaphors: Processor, Converter, etc
  • Evolves/Blurs over time
  • Hodge-podge of functionality in each object

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Procedures

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Procedures

  • Can i run this twice in a row?
  • Which order do I need to run these in?
  • Is it changing other parts of the program?
  • How does it interact with others?

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// associative�add(add(x, y), z) == add(x, add(y, z))��// commutative�add(x, y) == add(y, x)��// identity�add(x, 0) == x��// distributive�add(multiply(x, y), multiply(x, z)) == multiply(x, add(y,z))

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Functions with defined contracts

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Highly

generalized functions

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Composition

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Composition

  • Satisfy use cases
  • Simple, understandable pieces
  • Reuse

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  • Harder to change implementation
  • Harder for user to compose

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Composition

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  • Flexibility in implementation changes
  • Less use cases to support

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  • Flags, if/else
  • Won’t satisfy all cases
  • Less reuse

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Composition

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Favor

composable

functions, mostly

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CLI blog

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Exercises

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Code https://drive.google.com/file/d/1XQr5SZvTJ7dFYChr5kV42zO2FMhSATOa/view?usp=sharing

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