I'm Luke

@luke_dot_js

@lukewestby

@luke

builtwithelm.co

elm-http-builder

elm-template

elm-verbal-expressions

elm-community

Testability

Maintainability

Reliability

Today's Plan

• Talk about what Elm is
• Talk about what makes code untestable, unmaintainable, and unreliable
• Write some Elm
• Share resources for further learning

Elm

The best of functional programming in your browser

The best of functional programming...

• Immutable data structures
• Stateless functions
• Clean syntax
• Managed effects
• No confusing type constructs

... in your browser

• Compiles to JavaScript
• Highly performant Virtual DOM
• Good coverage of the web platform
• Easy JavaScript interop

Things that are not...

testable

• Mutable data
• Side-effects
• Implicit state

maintainable

• Untyped data and functions
• Unpredictable application structure
• Unmanaged module interactions
• Weak tools

reliable

• null

• Runtime errors
• Type errors
• Unpredictable package managers