Bridging the Divide: a noble quest of bootstraps, sugar, and spectral pyramids

A presentation at LambdaDays in February 2019 in Kraków, Poland by Brooklyn Zelenka

If you don’t like what you got Why don’t you change it If your programming language is all screwed up Rearrange it 🤘😈🔥 TROOPER, “RAISE A LIT TLE HELL” (SORT OF)

M E TA TA L K I N G A B O U T T H I S T A L K

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co 🔹 Ethereum Core Dev

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co 🔹 Ethereum Core Dev 📜 Authored bunch of standards

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co 🔹 Ethereum Core Dev 📜 Authored bunch of standards ⚛ FISSION Framework

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co 🔹 Ethereum Core Dev 📜 Authored bunch of standards ⚛ FISSION Framework 💬 Clarity Language

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co 🔹 Ethereum Core Dev 📜 Authored bunch of standards ⚛ FISSION Framework 💬 Clarity Language 🧙 Open Sourceress

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co 🧙 Open Sourceress 🔹 Ethereum Core Dev 🤓 PLT Enthusiast 📜 Authored bunch of standards ⚛ FISSION Framework 💬 Clarity Language

M E TA B R O O K LY N Z E L E N K A — @ E X P E D E ♠ CEO & Chief Scientist @ SPADE Co 🧙 Open Sourceress 🔹 Ethereum Core Dev 🤓 PLT Enthusiast 📜 Authored bunch of standards λ Founded VanFP ⚛ FISSION Framework 💬 Clarity Language

M E TA FOLLOW UP TO LOVE POTION NUMBER 9

M E TA STRUCTURE 🏛 • Philosophy • Principles

M E TA STRUCTURE 🏛 • Philosophy • Principles • Toy Example

M E TA STRUCTURE 🏛 • Philosophy • Principles • Toy Example • (Partly also an experience report 🤫)

M E TA WHY FOCUS ON LIBRARIES? 📚 • Much material on language design • Language ergonomics are an active area of research

M E TA WHY FOCUS ON LIBRARIES? 📚 • Much material on language design • Language ergonomics are an active area of research • Different constraints when working inside an existing language

M E TA C O D E I L L U S T R AT I O N S W I L L B E H I G H L E V E L

TOOLS OF THOUGHT 🛠🧠 A P P L I C AT I O N S C O M E A N D G O , B U T C O N C E P T S S TAY T H E S A M E

To think is to forget a difference, to generalize, to abstract 🙂 JORGE LUIS BORGES

TOOLS OF THOUGHT 🛠🧠 TOOLS & ME THODS > BIOLOGY 🏕🔥🚀

TOOLS OF THOUGHT 🛠🧠 TOOLS & ME THODS > BIOLOGY 🏕🔥🚀 • Possibly use our minds less than our ancestors

TOOLS OF THOUGHT 🛠🧠 TOOLS & ME THODS > BIOLOGY 🏕🔥🚀 • Possibly use our minds less than our ancestors • We have better mental tools 🏹🔥

TOOLS OF THOUGHT 🛠🧠 TOOLS & ME THODS > BIOLOGY 🏕🔥🚀 • Possibly use our minds less than our ancestors • We have better mental tools 🏹🔥 • Metric > Imperial

TOOLS OF THOUGHT 🛠🧠 TOOLS & ME THODS > BIOLOGY 🏕🔥🚀 • Possibly use our minds less than our ancestors • We have better mental tools 🏹🔥 • Metric > Imperial • Arabic numerals > Roman numerals

TOOLS OF THOUGHT 🛠🧠 N O T J U S T FA S T E R H O R S E S = 🏎

TOOLS OF THOUGHT 🛠🧠 N O T J U S T FA S T E R H O R S E S = 🏎 • Algorithms > hardware • Moore’s Law ending ☠ • Algorithms more beneficial to performance in many domains

TOOLS OF THOUGHT 🛠🧠 N O T J U S T FA S T E R H O R S E S = 🏎 • Algorithms > hardware • Moore’s Law ending ☠ • Algorithms more beneficial to performance in many domains • Abstraction very important to software quality • Because of the “human” part of HCI • (Of course a PLT person would say this 😜)

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality 🤔 Philosophy

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality 🤔 Philosophy 🔺 Abstraction

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality 🤔 Philosophy 🔺 Abstraction 💭 Concepts & Practice

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality 🤔 Philosophy 🔺 Abstraction 💭 Concepts & Practice 🗣 Grammar & Vocabulary

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality 🤔 Philosophy 🔺 Abstraction 💭 Concepts & Practice 🗣 Grammar & Vocabulary 📝 Concrete Code

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality 🤔 Philosophy 🔺 Abstraction 💭 Concepts & Practice 🗣 Grammar & Vocabulary 📝 Concrete Code ⚙ Machine

TOOLS OF THOUGHT 🛠🧠 P L AT O N I C I D E A L 👼 🌌 Reality 🤔 Philosophy 🔺 Abstraction 💭 Concepts & Practice 🗣 Grammar & Vocabulary 📝 Concrete Code ⚙ Machine 🎭 Real World Outcomes

TOOLS OF THOUGHT 🛠🧠 FORKING & BLENDING 🍰 🌌 🤔 🔺 💭 Context A 🗣 📝 ⚙ 🎭

TOOLS OF THOUGHT 🛠🧠 FORKING & BLENDING 🍰 🌌 🤔 🔺 💭 Context A 🗣 🗣 📝 📝 ⚙ 🎭 Context B

TOOLS OF THOUGHT 🛠🧠 LIBRARY SWEE T SPOTS 🍭

TOOLS OF THOUGHT 🛠🧠 LIBRARY SWEE T SPOTS 🍭 Generality • Low information • Few assumptions • Many use cases

TOOLS OF THOUGHT 🛠🧠 LIBRARY SWEE T SPOTS 🍭 Generality Power • Low information • High information • Few assumptions • Can make many assumptions • Many use cases • Tailored to few use cases

TOOLS OF THOUGHT 🛠🧠 A TA X O N O M Y O F L I B R A R I E S 📚

TOOLS OF THOUGHT 🛠🧠 A TA X O N O M Y O F L I B R A R I E S 📚 • Generality • ex. Witchcraft, Database Adapters

TOOLS OF THOUGHT 🛠🧠 A TA X O N O M Y O F L I B R A R I E S 📚 • Generality • ex. Witchcraft, Database Adapters • Framework • ex. Phoenix, Nerves

TOOLS OF THOUGHT 🛠🧠 A TA X O N O M Y O F L I B R A R I E S 📚 • Generality • ex. Witchcraft, Database Adapters • Framework • ex. Phoenix, Nerves • Feature Emulation • ex. TypeClass

PORTING PRINCIPLES STRE TCHING WITHOUT SNAPPING 💥

It’s dangerous to go alone! Take this [advice]!

PORTING PRINCIPLES M O T I VAT I O N 🥕 • Two styles of Scala 1. Java without the braces 2. Haskell fan fiction

PORTING PRINCIPLES M O T I VAT I O N 🥕 • Two styles of Scala 1. Java without the braces 2. Haskell fan fiction • “I’d need to convert my entire project for this lib to make sense” 👎

PORTING PRINCIPLES I, LIBRARY 🤖
Context Independence Each unit of code must be able to be taken on its own. An extension may not break nor alter the runtime semantics of either enclosed or exterior code.

PORTING PRINCIPLES
Context Independence Each unit of code must be able to be taken on its own. An extension may not break nor alter the runtime semantics of either enclosed or exterior code. 2. Ethos An extension must remain consistent with the character of the host language and broadest community standards, except where such consistency would conflict with the First Law. 3. Completeness An extension must introduce or integrate its concept(s) as completely as possible, as long as such constructs do not conflict with the First or Second Laws.

PORTING PRINCIPLES HEY! LISTEN! 🧚 1. Courage ⚔ Each unit of code must be able to be taken on its own. An extension may not break nor alter the runtime semantics of either enclosed or exterior code. 2. Wisdom 📚 An extension must remain consistent with the character of the host language and broadest community standards, except where such consistency would conflict with the First Law. 3. Power 🚀 An extension must introduce or integrate its concept(s) as completely as possible, as long as such constructs do not conflict with the First or Second Laws.

CONTEXT INDEPENDENCE THE COURAGE TO VENTURE ALONE ⚔

The art of programming is the art of organizing complexity, of mastering multitude, and avoiding its bastard chaos as effectively as possible 🧘 EDSGER DIJKSTRA

Each unit of code must be able to be taken on its own. An extension must not break nor alter the runtime semantics of either enclosed or exterior code.

CONTEXT INDEPENDENCE I N D E P E N D E N C E D AY 🛸

CONTEXT INDEPENDENCE I N D E P E N D E N C E D AY 🛸 • Clarity, composability, and unambiguity • Same class of thing as referential transparency • Especially important with FP assumptions • Each chunk of code (horizontal or vertical) should be comprehensible on its own • Most common: behaviour depending on implicit or hidden state

CONTEXT INDEPENDENCE M A C R O S O K AY • Despite structural changes from macros • No macro mangle 🙅 • You have to try pretty hard to break this in Elixir

CONTEXT INDEPENDENCE CASE STUDY: Algae • Concept: Bootstrap structs into ADTs

CONTEXT INDEPENDENCE CASE STUDY: Algae • Concept: Bootstrap structs into ADTs • Takeaway: Composition, orthogonality, structured abstraction

CONTEXT INDEPENDENCE CASE STUDY: Algae • Concept: Bootstrap structs into ADTs • Takeaway: Composition, orthogonality, structured abstraction • Removes nothing

CONTEXT INDEPENDENCE CASE STUDY: Algae All the features!

CONTEXT INDEPENDENCE 42 CASE STUDY: Algae 77 All the features! 1234 98 32

ETHOS T H E W I S D O M TO B A L A N C E C O N S I ST E N CY, C H A N G E , A N D R E ST R A I N T 📚

The utility of a language as a tool of thought increases with the range of topics it can treat, but decreases with the amount of vocabulary and the complexity of grammatical rules which the user must keep in mind 🎛 KENNETH IVERSON

An extension must remain consistent with the character of the host language and broadest community standards, except where such consistency would conflict with the First Law.

ETHOS A M AT T E R O F C H A R A C T E R

ETHOS A M AT T E R O F C H A R A C T E R • Ethos — noun. (/ˈiːθɒs/ or US: /ˈiːθoʊs/) The fundamental character or spirit of a culture; the underlying sentiment that informs the beliefs, customs, or practices of a group or society; dominant assumptions of a people or period • Like all interesting things, it’s the fuzziest • Feel as close to the host language as possible • But also blending in features from a target

ETHOS CASE STUDY: Exceptional’S PIPES • Concept: Flow-ability is very core to Elixir’s ethos • Kernel.|>/2

ETHOS CASE STUDY: Exceptional’S PIPES • Concept: Flow-ability is very core to Elixir’s ethos • Kernel.|>/2 • Consistent flow metaphor / punning on existing metaphor • Exceptional: ~>/2 and >>>/2

ETHOS CASE STUDY: TUPLES VS EXCEPTIONS • Even internal tradeoffs in Elixir’s Kernel design

ETHOS CASE STUDY: TUPLES VS EXCEPTIONS • Even internal tradeoffs in Elixir’s Kernel design • Fully adhering to the underlying Elixir’s ethos • I get the most positive feedback from Exceptional

ETHOS STRONG CHARACTER • Languages like C, Haskell, Rust, Elm, and Golang stand for something

ETHOS STRONG CHARACTER • Languages like C, Haskell, Rust, Elm, and Golang stand for something • Erlang designed for a practical application: telecom switches • Erlang happened to land on FP

INTERLUDE WHEREFORE ART THOU FUNCTIONAL PROGRAMMING? 🌹

INTERLUDE W H AT ’ S S O G R E AT A B O U T F P A N Y W AY ? 🥳

INTERLUDE W H AT ’ S S O G R E AT A B O U T F P A N Y W AY ? 🥳 • Modularity • Composition • Can describe general solutions via abstraction! • Make the large feel like the small & fewer patterns to memorize Z • Maleable code • HOFs transform your programs on the fly ⚗ • ex. Enum.map/2 can be seen as adapting every item in a structure (operational), or as transforming the functor

INTERLUDE O P E R AT I O N A L V S D E N O TAT I O N A L T H I N K I N G

INTERLUDE O P E R AT I O N A L V S D E N O TAT I O N A L T H I N K I N G • Enum.map/2 can be seen through the lens of… • Data • A cleaner for loop (operational) • Run a function on every item in a structure • Programs • Transforms the input program into a new program

INTERLUDE FUNCTIONAL ALCHEMY ⚗ @spec long_form(integer()) :: String.t()

INTERLUDE FUNCTIONAL ALCHEMY ⚗ @spec long_form(integer()) :: String.t() @spec long_forms([integer()]) :: [String.t()]

INTERLUDE FUNCTIONAL ALCHEMY ⚗ @spec long_form(integer()) :: String.t() Enum.map/2 @spec long_forms([integer()]) :: [String.t()]

INTERLUDE FUNCTIONAL ALCHEMY ⚗ integer() String.t() Enum.map/2 [integer()] [String.t()]

INTERLUDE W H AT ’ S S O T E R R I B L E A B O U T F P A N Y W AY ? 😱

INTERLUDE W H AT ’ S S O T E R R I B L E A B O U T F P A N Y W AY ? 😱 • The Church Chasm • If you have a hammer, everything looks like a nail • “Use anonymous functions for everything! Aren’t closures amazing?!” • Can focus on mechanics rather than concepts • Explicit state = lots of explicit handling, “pass the world”, &c • A tendency towards the darkest of magics

INTERLUDE {:tarpit, “tradeoffs”} • Surface simplicity has a cost • Complex in the large • Restricted domain in the small

INTERLUDE {:tarpit, “tradeoffs”} • Surface simplicity has a cost • Takeaway: strive for • Complex in the large • Orthogonality • Restricted domain in the small • Generality • Extensibility

INTERLUDE ACTOR ABYSS • Each step is very simple

INTERLUDE ACTOR ABYSS • Each step is very simple • Reasoning about dynamic organisms is hard • Remember to store your data for crash recovery • Called collaborator may not be there

INTERLUDE LANGUAGE SPECTRUM Imperative Declarative

INTERLUDE LANGUAGE PYRAMID Dynamic Operational Mechanistic 🚂 •→• Universal ↓ ↓ Denotational •→• Mathematics ] Contextual Semiotic Linguistic

INTERLUDE LANGUAGE PYRAMID Dynamic Operational Mechanistic 🚂 •→• Universal ↓ ↓ Denotational •→• Mathematics Overall historical trend ] Contextual Semiotic Linguistic

INTERLUDE LANGUAGE PYRAMID •→• Universal ↓ ↓ Denotational •→• Mathematics 🌌 🤔 🔺 💭 🗣 📝 ⚙ 🎭 Dynamic Operational Mechanistic 🚂 Overall historical trend ] Contextual Semiotic Linguistic

ETHOS T H E P I P E S S T R AT E G Y • A break in ethos from Erlang

ETHOS T H E P I P E S S T R AT E G Y • A break in ethos from Erlang • Fits Elixir’s strategy • Clean • Easy to follow • Similar to OO’s fluent interfaces

ETHOS T H E P I P E S S T R AT E G Y • A break in ethos from Erlang • Fits Elixir’s strategy • Clean • Easy to follow • Similar to OO’s fluent interfaces • Helps to read like English

ETHOS T H E P I P E S S T R AT E G Y • A break in ethos from Erlang • Fits Elixir’s strategy • Tradeoffs • Operational/mechanistic mode of thought • Clean • Cleans up a lot of code • Easy to follow • Focus or “zoom” effect 🔭 • Similar to OO’s fluent interfaces • Zooming doesn’t really apply to actors • Helps to read like English

ETHOS G U E S T L A N G U A G E S Y N TA X E S

ETHOS G U E S T L A N G U A G E S Y N TA X E S • Which language is this?

ETHOS G U E S T L A N G U A G E S Y N TA X E S • Which language is this? • Does it matter?

ETHOS G U E S T L A N G U A G E S Y N TA X E S • Which language is this? • Does it matter? • Is this appropriate?

COMPLETENESS THE POWER OF THE DARK SIDE 💪

COMPLETENESS THE POWER OF HARMONIOUS TOOLS 💪

The limits of my language mean the limits of my world 🙊 LUDWIG WIT TGENSTEIN

An extension must introduce or integrate its concept(s) as completely as possible, as long as such constructs do not conflict with the First or Second Laws.

COMPLETENESS SWEE T SPOTS NEED NOT BE SUGARY a🍭

COMPLETENESS SWEE T SPOTS NEED NOT BE SUGARY a🍭 • Synergistic combinators

COMPLETENESS SWEE T SPOTS NEED NOT BE SUGARY a🍭 • Synergistic combinators • ↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵

COMPLETENESS SWEE T SPOTS NEED NOT BE SUGARY a🍭 • Synergistic combinators • ↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ • ~60 symbols, depending

COMPLETENESS SWEE T SPOTS NEED NOT BE SUGARY a🍭 • Synergistic combinators • ↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ • ~60 symbols, depending • “Idioms over libraries”

COMPLETENESS SWEE T SPOTS NEED NOT BE SUGARY a🍭 • Synergistic combinators • ↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ • ~60 symbols, depending • “Idioms over libraries” • More than the sum of their parts

COMPLETENESS INCOMPLETENESS 😡 • Often see attempts to add “just the parts I care about”

COMPLETENESS INCOMPLETENESS 😡 • Often see attempts to add “just the parts I care about” • ex. Only %Maybe{} and bind/2 in a library

COMPLETENESS INCOMPLETENESS 😡 • Often see attempts to add “just the parts I care about” • ex. Only %Maybe{} and bind/2 in a library • Could have exponentially more utility!

COMPLETENSS CASE STUDY: Witchcraft • You can go pretty far with extension if you have a macros • ex. TypeClass

COMPLETENSS CASE STUDY: Witchcraft • You can go pretty far with extension if you have a macros • ex. TypeClass • Update, clean, and power up Kernel functions • Curried, async, flipped variants

CASE STUDY: Witchcraft SOURCES ⛲ • Cat Theory → Haskell & PureScript & Elm &c → Witchcraft

CASE STUDY: Witchcraft SOURCES ⛲ • Cat Theory → Haskell & PureScript & Elm &c → Witchcraft • Clean up the type class hierarchy • Haskell • Purescript • Fantasy Land Specification • and others

CASE STUDY: Witchcraft KEEPIN’ IT WITCHY d

CASE STUDY: Witchcraft KEEPIN’ IT WITCHY d • Imported things with immediate synergy

CASE STUDY: Witchcraft KEEPIN’ IT WITCHY d • Imported things with immediate synergy • Easy with type class hierarchies

CASE STUDY: Witchcraft KEEPIN’ IT WITCHY d • Imported things with immediate synergy • Easy with type class hierarchies • Renamed many functions for clarity

CASE STUDY: Witchcraft liftM/liftM2/liftM3/liftM4 → lift/*

CASE STUDY: Witchcraft liftM/liftM2/liftM3/liftM4 → lift/* • Arity came in handy in a few places 🙌 • Collaborator functions renamed for metaphors so pipes make sense 😭 • Sometime have to think nonlinearly

CASE STUDY: Witchcraft TypeClass • Fully desugars into • Modules • Protocols

CASE STUDY: Witchcraft TypeClass • Fully desugars into • Modules • Protocols • Tons of sugar

CASE STUDY: Witchcraft TypeClass • Fully desugars into • Modules • Protocols • Tons of sugar • Generates a bunch of code

CASE STUDY: Witchcraft TypeClass • Fully desugars into • Modules • Protocols • Tons of sugar • Generates a bunch of code • A completeness pattern • Functions for free!

CASE STUDY: Witchcraft COMPLETENESS COROLLARY: MODULARITY

CASE STUDY: Witchcraft COMPLETENESS COROLLARY: MODULARITY • Breaking up Witchcraft libs was a very good idea • Balance how much each lib should do • Marketed as more reusable 😉

CASE STUDY: Witchcraft TA K E A W AY S • Specs > Libraries • Think about how languages flow, and other physical metaphors • Naming is very important, especially with directionality • Balance between source and target language audiences • ie: folks coming from Haskell to Elixir, and from Elixir to these concepts

A N T I PA T T E R N S GETTING IT WRONG i

Experience is the name everyone gives to their mistakes 💔 O S C A R W I L D E , “L A DY W I N D E R M E R E ’ S FA N “

A N T I PAT T E R N S TORCHES AND PITCHFORKS

A N T I PAT T E R N S TORCHES AND PITCHFORKS If you feel like this you’ve probably created a monster

A N T I PAT T E R N S MIND TRAPS 🕳🧠 • Identify the way you tend to fail

A N T I PAT T E R N S MIND TRAPS 🕳🧠 • Identify the way you tend to fail • My failure mode is to enforce correctness

A N T I PAT T E R N S MIND TRAPS 🕳🧠 • Identify the way you tend to fail • My failure mode is to enforce correctness • Harder in libraries than in application code, since you have such control • Great definitional power comes with great responsibility to your users!

A N T I PAT T E R N S FORCE PRACTICES ON USERS

A N T I PAT T E R N S FORCE PRACTICES ON USERS • Overall very happy with TypeClass • Contains my biggest regret 😖

A N T I PAT T E R N S FORCE PRACTICES ON USERS • Overall very happy with TypeClass • Contains my biggest regret 😖 • Enforced prop testing at compile time • Slow • Detracts people from using the lib ✅

A N T I PAT T E R N S REDEFINE / OVERWRITE Kernel

A N T I PAT T E R N S REDEFINE / OVERWRITE Kernel a

A N T I PAT T E R N S A L L T H E O P E R AT O R S

A N T I PAT T E R N S A L L T H E O P E R AT O R S • Super duper handy to have 🎉

A N T I PAT T E R N S A L L T H E O P E R AT O R S • Super duper handy to have 🎉 • Limited number of operators in Elixir

A N T I PAT T E R N S A L L T H E O P E R AT O R S • Super duper handy to have 🎉 • Limited number of operators in Elixir • Operator-space collisions 💥

A N T I PAT T E R N S A L L T H E O P E R AT O R S • Super duper handy to have 🎉 • Limited number of operators in Elixir • Operator-space collisions 💥 • Handy if you’re user has one lib per application, but you don’t know

A N T I PAT T E R N S T H E O P T I O N T O D I S A M B I G U AT E

A N T I PAT T E R N S T H E O P T I O N T O D I S A M B I G U AT E What does this do?

PUT TING IT ALL TOGE THER 🏗 LET’S PORT A THING 🛳

PUT TING IT ALL TOGE THER 🏗 TOY EXAMPLE 🧸

PUT TING IT ALL TOGE THER 🏗 TOY EXAMPLE 🧸 • What to port? 🤔

PUT TING IT ALL TOGE THER 🏗 TOY EXAMPLE 🧸 • What to port? 🤔 Imperative Declarative

PUT TING IT ALL TOGE THER 🏗 TOY EXAMPLE 🧸 • What to port? 🤔 • Witchcraft already exists Imperative Declarative

PUT TING IT ALL TOGE THER 🏗 TOY EXAMPLE 🧸 • What to port? 🤔 • Witchcraft already exists • Let’s go the opposite direction Imperative Declarative

PUT TING IT ALL TOGE THER 🏗 F E AT U R E S

PUT TING IT ALL TOGE THER 🏗 F E AT U R E S • Classes • Mutable instance variables • Constructor • Methods (static and non-static) • Dot notation & chaining • Duck typing 🦆

PUT TING IT ALL TOGE THER 🏗 GOING WHOLE-HOG 🐖

PUT TING IT ALL TOGE THER 🏗 GOING WHOLE-HOG 🐖 • Data hiding • All functionality behind a single interface • Essentially a struct • Instance variables persist between calls • Not going to handle inheritance, but totally possible • TypeClass does something similar

PUT TING IT ALL TOGE THER 🏗 STEPPING BACK FROM THE BRINK v

PUT TING IT ALL TOGE THER 🏗 STEPPING BACK FROM THE BRINK v • Too far! Revert! Revert! • 🤔 This pattern isn’t that uncommon • Aside from the dot chaining 😱 • Typically use GenServer or Agent • What can we step back?

PUT TING IT ALL TOGE THER 🏗 GARNET V2 ♦ ❌ struct or builder

PUT TING IT ALL TOGE THER 🏗 GARNET V2 ♦ ❌ struct or builder ❌ anonymous functions

PUT TING IT ALL TOGE THER 🏗 GARNET V2 ♦ ❌ struct or builder ❌ anonymous functions (Much simpler to implement)

F I N A L TA K E A W AY S 📦 THE HIGH LEVEL REVIEW 👀

F I N A L TA K E A W AY S 📦 BIG THEMES • Standard libs are not sacred • But all lib code should feel like it belongs in there! • Just because you can doesn’t mean you should

Like punning, programming is a play on words 📚 AL AN J. PERLIS

THANK YOU, KRAKÓW z🎉 @EXPEDE GITHUB.COM/EXPEDE H E L L O @ B R O O K LY N Z E L E N K A . C O M

Brooklyn Zelenka
@expede

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Ever wished that you had feature X in language Y? Frustrated that two libraries don’t play nice together? Have framework fatigue? Language design principles also extend to libraries. This is especially true when porting concepts and features from another language or ecosystem. In this follow-up to her Empex 2018 keynote, Brooklyn will explore a philosophy of library design with an eye towards porting, drawing concretely from her experiences bootstrapping features primarily inspired by Haskell and OCaml to Elixir. Which factors do you need to balance, when is it appropriate to deviate from the core syntax (of both source and target), and importantly: how far can you bend before you break?

Bridging the Divide: a noble quest of bootstraps, sugar, and spectral pyramids

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