Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Scenic City Summit 2017: Tame the frontend with...
Search
Jeremy Fairbank
July 28, 2017
Programming
0
170
Scenic City Summit 2017: Tame the frontend with Elm
Jeremy Fairbank
July 28, 2017
Tweet
Share
More Decks by Jeremy Fairbank
See All by Jeremy Fairbank
Connect.Tech 2020: Advanced Cypress Testing
jfairbank
1
210
CodeMash 2020: Solving the Boolean Identity Crisis
jfairbank
1
160
CodeMash 2020: Practical Functional Programming
jfairbank
1
330
Connect.Tech 2019: Practical Functional Programming
jfairbank
0
360
Connect.Tech 2019: Solving the Boolean Identity Crisis
jfairbank
0
180
Lambda Squared 2019: Solving the Boolean Identity Crisis
jfairbank
0
130
All Things Open 2018: Practical Functional Programming
jfairbank
2
270
Connect.Tech 2018: Effective React Testing
jfairbank
1
170
Fluent Conf 2018: Building web apps with Elm Tutorial
jfairbank
2
860
Other Decks in Programming
See All in Programming
デミカツ切り抜きで面倒くさいことはPythonにやらせよう
aokswork3
0
220
uniqueパッケージの内部実装を支えるweak pointerの話
magavel
0
960
Django Ninja による API 開発効率化とリプレースの実践
kashewnuts
0
1.2k
CSC509 Lecture 01
javiergs
PRO
1
440
Domain-centric? Why Hexagonal, Onion, and Clean Architecture Are Answers to the Wrong Question
olivergierke
2
790
Advance Your Career with Open Source
ivargrimstad
0
450
いま中途半端なSwift 6対応をするより、Default ActorやApproachable Concurrencyを有効にしてからでいいんじゃない?
yimajo
2
390
なぜGoのジェネリクスはこの形なのか? Featherweight Goが明かす設計の核心
ryotaros
7
1.1k
Web フロントエンドエンジニアに開かれる AI Agent プロダクト開発 - Vercel AI SDK を観察して AI Agent と仲良くなろう! #FEC余熱NIGHT
izumin5210
3
490
Cursorハンズオン実践!
eltociear
2
770
CSC509 Lecture 05
javiergs
PRO
0
300
NetworkXとGNNで学ぶグラフデータ分析入門〜複雑な関係性を解き明かすPythonの力〜
mhrtech
3
1.2k
Featured
See All Featured
Writing Fast Ruby
sferik
629
62k
Docker and Python
trallard
46
3.6k
Embracing the Ebb and Flow
colly
88
4.8k
Building a Modern Day E-commerce SEO Strategy
aleyda
43
7.7k
ピンチをチャンスに:未来をつくるプロダクトロードマップ #pmconf2020
aki_iinuma
127
53k
The Cost Of JavaScript in 2023
addyosmani
53
9k
The Web Performance Landscape in 2024 [PerfNow 2024]
tammyeverts
9
860
Music & Morning Musume
bryan
46
6.8k
Creating an realtime collaboration tool: Agile Flush - .NET Oxford
marcduiker
32
2.3k
GitHub's CSS Performance
jonrohan
1032
470k
The Pragmatic Product Professional
lauravandoore
36
6.9k
Imperfection Machines: The Place of Print at Facebook
scottboms
269
13k
Transcript
Tame the frontend with Elm Jeremy Fairbank @elpapapollo / jfairbank
Tame the frontend with Elm Jeremy Fairbank @elpapapollo / jfairbank
Software is broken. We are here to fix it. Say
[email protected]
Happiness
None
✓ Easier to write code ✓ Easier to write tests
✓ Easier to refactor
elm
No runtime exceptions in practice.
No undefined is not a function
Fast
One framework. No fatigue. Update View Model Messages
elm
Functional
greet name = "Hello, " ++ name greet "Scenic City
Summit" -- Hello, Scenic City Summit
greet name = "Hello, " ++ name greet "Scenic City
Summit" -- Hello, Scenic City Summit
greet name = "Hello, " ++ name greet "Scenic City
Summit" -- Hello, Scenic City Summit
greet name = "Hello, " ++ name greet "Scenic City
Summit" -- Hello, Scenic City Summit Single Expression
greet name = "Hello, " ++ name greet "Scenic City
Summit" -- Hello, Scenic City Summit
greet name = "Hello, " ++ name greet "Scenic City
Summit" -- Hello, Scenic City Summit
Pure Data in Data out
Pure No side effects
Pure Predictable and Testable!
add x y = x + y add 2 3
== 5 add 2 3 == 5 add 2 3 == 5
add x y = x + y add 2 3
== 5 add 2 3 == 5 add 2 3 == 5
add x y = x + y add 2 3
== 5 add 2 3 == 5 add 2 3 == 5
Expressive Terse and declarative code
function doubleNumbers(numbers) { const doubled = []; const l =
numbers.length; for (let i = 0; i < l; i++) { doubled.push(numbers[i] * 2); } return doubled; } doubleNumbers([1, 2, 3, 4, 5]); // [2, 4, 6, 8, 10] Imperative
function doubleNumbers(numbers) { const doubled = []; const l =
numbers.length; for (let i = 0; i < l; i++) { doubled.push(numbers[i] * 2); } return doubled; } doubleNumbers([1, 2, 3, 4, 5]); // [2, 4, 6, 8, 10] Imperative ×
myList = [1, 2, 3, 4, 5] double n =
n * 2 doubleNumbers list = List.map double list doubleNumbers myList -- [2, 4, 6, 8, 10]
myList = [1, 2, 3, 4, 5] double n =
n * 2 doubleNumbers list = List.map double list doubleNumbers myList -- [2, 4, 6, 8, 10]
myList = [1, 2, 3, 4, 5] double n =
n * 2 doubleNumbers list = List.map double list doubleNumbers myList -- [2, 4, 6, 8, 10]
myList = [1, 2, 3, 4, 5] double n =
n * 2 doubleNumbers list = List.map double list doubleNumbers myList -- [2, 4, 6, 8, 10]
myList = [1, 2, 3, 4, 5] double n =
n * 2 doubleNumbers list = List.map double list doubleNumbers myList -- [2, 4, 6, 8, 10]
myList = [1, 2, 3, 4, 5] double n =
n * 2 doubleNumbers list = List.map double list doubleNumbers myList -- [2, 4, 6, 8, 10]
Curried Functions Building blocks
add x y = x + y add 1 2
-- 3 (add 1) 2 -- 3
add x y = x + y add 1 2
-- 3 (add 1) 2 -- 3
add x y = x + y add 1 2
-- 3 (add 1) 2 -- 3
add x y = x + y add 1 2
-- 3 (add 1) 2 -- 3 New function created
increment = add 1 increment 2 -- 3 increment 41
-- 42
increment = add 1 increment 2 -- 3 increment 41
-- 42
increment = add 1 increment 2 -- 3 increment 41
-- 42
Pipes Compose functions with expressive chaining
greet name = "Hello, " ++ name exclaim phrase =
phrase ++ "!" excitedGreeting name = exclaim (greet (String.toUpper name))
greet name = "Hello, " ++ name exclaim phrase =
phrase ++ "!" excitedGreeting name = exclaim (greet (String.toUpper name))
excitedGreeting name = name |> String.toUpper |> greet |> exclaim
excitedGreeting "Tucker"
excitedGreeting name = name |> String.toUpper |> greet |> exclaim
excitedGreeting "Tucker"
"Tucker" |> String.toUpper |> greet |> exclaim
|> String.toUpper "Tucker" |> greet |> exclaim
"TUCKER" |> greet |> exclaim
|> greet "TUCKER" |> exclaim
"Hello, TUCKER" |> exclaim
|> exclaim "Hello, TUCKER"
"Hello, TUCKER!"
No Runtime Exceptions
Strong Static Types life : Int life = 42 greeting
: String greeting = "Hello World" isTrue : Bool isTrue = True numbers : List Int numbers = [1, 2, 3]
Strong Static Types life : Int life = 42 greeting
: String greeting = "Hello World" isTrue : Bool isTrue = True numbers : List Int numbers = [1, 2, 3]
Strong Static Types life : Int life = 42 greeting
: String greeting = "Hello World" isTrue : Bool isTrue = True numbers : List Int numbers = [1, 2, 3]
Strong Static Types life : Int life = 42 greeting
: String greeting = "Hello World" isTrue : Bool isTrue = True numbers : List Int numbers = [1, 2, 3]
Strong Static Types life : Int life = 42 greeting
: String greeting = "Hello World" isTrue : Bool isTrue = True numbers : List Int numbers = [1, 2, 3]
greet : String -> String greet name = "Hello, "
++ name add : Int -> Int -> Int add x y = x + y
greet : String -> String greet name = "Hello, "
++ name add : Int -> Int -> Int add x y = x + y
greet : String -> String greet name = "Hello, "
++ name add : Int -> Int -> Int add x y = x + y
greet : String -> String greet name = "Hello, "
++ name add : Int -> (Int -> Int) add x y = x + y
The 2nd argument to function `add` is causing a mismatch.
7| add 2 "3" ^^^ Function `add` is expecting the 2nd argument to be: Int But it is: String Compile time static type checks
Immutable Data Safe and Consistent
dog : { name : String, age : Int }
dog = { name = "Tucker" , age = 11 } dog.name -- "Tucker" dog.age -- 11 Records
dog : { name : String, age : Int }
dog = { name = "Tucker" , age = 11 } dog.name -- "Tucker" dog.age -- 11 Records
dog : { name : String, age : Int }
dog = { name = "Tucker" , age = 11 } dog.name -- "Tucker" dog.age -- 11 Records
dog : { name : String, age : Int }
dog = { name = "Tucker" , age = 11 } dog.name -- "Tucker" dog.age -- 11 Records
haveBirthday dog = { dog | age = dog.age +
1 } dog = { name = "Tucker", age = 11 } olderDog = haveBirthday dog olderDog.age -- 12 olderDog.name -- "Tucker" dog.age -- 11 dog.name -- "Tucker" Create New Data
haveBirthday dog = { dog | age = dog.age +
1 } dog = { name = "Tucker", age = 11 } olderDog = haveBirthday dog olderDog.age -- 12 olderDog.name -- "Tucker" dog.age -- 11 dog.name -- "Tucker" Create New Data
haveBirthday dog = { dog | age = dog.age +
1 } dog = { name = "Tucker", age = 11 } olderDog = haveBirthday dog olderDog.age -- 12 olderDog.name -- "Tucker" dog.age -- 11 dog.name -- "Tucker" Create New Data
haveBirthday dog = { dog | age = dog.age +
1 } dog = { name = "Tucker", age = 11 } olderDog = haveBirthday dog olderDog.age -- 12 olderDog.name -- "Tucker" dog.age -- 11 dog.name -- "Tucker" Create New Data
haveBirthday dog = { dog | age = dog.age +
1 } dog = { name = "Tucker", age = 11 } olderDog = haveBirthday dog olderDog.age -- 12 olderDog.name -- "Tucker" dog.age -- 11 dog.name -- "Tucker" Create New Data
haveBirthday dog = { dog | age = dog.age +
1 } dog = { name = "Tucker", age = 11 } olderDog = haveBirthday dog olderDog.age -- 12 olderDog.name -- "Tucker" dog.age -- 11 dog.name -- "Tucker" Create New Data
Custom Types Domain-specific code
type alias Dog = { name : String , age
: Int , breed : Breed } type Breed = Sheltie | Poodle
type alias Dog = { name : String , age
: Int , breed : Breed } type Breed = Sheltie | Poodle
type alias Dog = { name : String , age
: Int , breed : Breed } type Breed = Sheltie | Poodle Union Type
dog : Dog dog = { name = "Tucker" ,
age = 11 , breed = Sheltie }
dog : Dog dog = { name = "Tucker" ,
age = 11 , breed = Sheltie }
dog : Dog dog = { name = "Tucker" ,
age = 11 , breed = Sheltie }
dog : Dog dog = { name = "Tucker" ,
age = 11 , breed = Shelty } Misspelled. Won’t compile!
No null or undefined
type Maybe a = Just a | Nothing
type Maybe a = Just a | Nothing Wraps the
successful value
type Maybe a = Just a | Nothing Wraps the
successful value Type Variable
type Maybe a = Just a | Nothing Represents no
result or missing value
type Maybe a = Just a | Nothing Either I
have Just the value a, or I have Nothing.
divide : Float -> Float -> Maybe Float divide x
y = if y == 0 then Nothing else Just (x / y) divide 4 2 -- Just 2 divide 4 0 -- Nothing
divide : Float -> Float -> Maybe Float divide x
y = if y == 0 then Nothing else Just (x / y) divide 4 2 -- Just 2 divide 4 0 -- Nothing
divide : Float -> Float -> Maybe Float divide x
y = if y == 0 then Nothing else Just (x / y) divide 4 2 -- Just 2 divide 4 0 -- Nothing
divide : Float -> Float -> Maybe Float divide x
y = if y == 0 then Nothing else Just (x / y) divide 4 2 -- Just 2 divide 4 0 -- Nothing
divide : Float -> Float -> Maybe Float divide x
y = if y == 0 then Nothing else Just (x / y) divide 4 2 -- Just 2 divide 4 0 -- Nothing
divide : Float -> Float -> Maybe Float divide x
y = if y == 0 then Nothing else Just (x / y) divide 4 2 -- Just 2 divide 4 0 -- Nothing
case divide 4 2 of Just n -> "Result is
" ++ (toString n) Nothing -> "No Result"
case divide 4 2 of Just n -> "Result is
" ++ (toString n) Nothing -> "No Result"
case divide 4 2 of Just n -> "Result is
" ++ (toString n) Nothing -> "No Result"
case divide 4 2 of Just n -> "Result is
" ++ (toString n) Nothing -> "No Result"
case divide 4 2 of Just n -> "Result is
" ++ (toString n) -- Nothing -> -- "No Result"
Exhaustive matching This `case` does not have branches for all
possibilities. 21|> case divide 4 2 of 22|> Just n -> 23|> "Result is " ++ (toString n) You need to account for the following values: Maybe.Nothing Add a branch to cover this pattern!
Update View Model Messages The Elm Architecture
model Update View
model Update View VDOM
model Update View
model Update View
model Update View
model Update View
model Update View
model Update View VDOM
Demos The Elm Architecture in Action
Getting Started • elm-lang.org • elm-lang.org/examples • guide.elm-lang.org • www.elm-tutorial.org
• builtwithelm.co • Slack • elmlang.herokuapp.com
Thanks! Jeremy Fairbank @elpapapollo / jfairbank Slides: bit.ly/scs-elm