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
160
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
190
CodeMash 2020: Solving the Boolean Identity Crisis
jfairbank
1
130
CodeMash 2020: Practical Functional Programming
jfairbank
1
310
Connect.Tech 2019: Practical Functional Programming
jfairbank
0
330
Connect.Tech 2019: Solving the Boolean Identity Crisis
jfairbank
0
170
Lambda Squared 2019: Solving the Boolean Identity Crisis
jfairbank
0
110
All Things Open 2018: Practical Functional Programming
jfairbank
2
250
Connect.Tech 2018: Effective React Testing
jfairbank
1
140
Fluent Conf 2018: Building web apps with Elm Tutorial
jfairbank
2
820
Other Decks in Programming
See All in Programming
楽しく向き合う例外対応
okutsu
0
680
AIの力でお手軽Chrome拡張機能作り
taiseiue
0
190
Django NinjaによるAPI開発の効率化とリプレースの実践
kashewnuts
1
260
AIプログラミング雑キャッチアップ
yuheinakasaka
18
4.5k
パスキーのすべて ── 導入・UX設計・実装の紹介 / 20250213 パスキー開発者の集い
kuralab
3
900
ファインディLT_ポケモン対戦の定量的分析
fufufukakaka
0
920
バッチを作らなきゃとなったときに考えること
irof
2
530
密集、ドキュメントのコロケーション with AWS Lambda
satoshi256kbyte
1
210
Djangoアプリケーション 運用のリアル 〜問題発生から可視化、最適化への道〜 #pyconshizu
kashewnuts
1
260
SwiftUI Viewの責務分離
elmetal
PRO
2
270
Datadog Workflow Automation で圧倒的価値提供
showwin
1
170
Amazon Q Developer Proで効率化するAPI開発入門
seike460
PRO
0
120
Featured
See All Featured
Six Lessons from altMBA
skipperchong
27
3.6k
GitHub's CSS Performance
jonrohan
1030
460k
How GitHub (no longer) Works
holman
314
140k
The Power of CSS Pseudo Elements
geoffreycrofte
75
5.5k
Bootstrapping a Software Product
garrettdimon
PRO
306
110k
What’s in a name? Adding method to the madness
productmarketing
PRO
22
3.3k
The Art of Delivering Value - GDevCon NA Keynote
reverentgeek
10
1.3k
Product Roadmaps are Hard
iamctodd
PRO
50
11k
Rebuilding a faster, lazier Slack
samanthasiow
80
8.9k
Fight the Zombie Pattern Library - RWD Summit 2016
marcelosomers
233
17k
Optimizing for Happiness
mojombo
376
70k
Fantastic passwords and where to find them - at NoRuKo
philnash
51
3k
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