Intro to
Elm
Jeremy Fairbank
@elpapapollo / jfairbank
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Software is broken.
We are here to fix it.
Say hi@testdouble.com
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Functional and statically typed
programming language for frontend
development
elm
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Web and UI Focused
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Compiles to JavaScript
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No runtime exceptions in
practice.
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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
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Functional
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Pure Data in
Data out
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Pure No side
effects
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Pure Predictable
and Testable!
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Immutable Data
• Safety and consistency
• Explicit flow of data
• No subtle mutation bugs
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No undefined is not a
function
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Fast
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One framework.
No fatigue.
Update
View
Model
Messages
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VDOM
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VDOM
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✓ Easier to write code
✓ Easier to write tests
✓ Easier to refactor