Singletons and You in Haskell

on YouTube ↗12m

" summary

Shows how Richard Eisenberg's singletons library actually gives runtime witnesses so type-level states become usable values, illustrated by a GADT Door state example (open closed locked). Demonstrates how the library generates singletons for free and provides instances to turn types into witness values that let code pattern match on types, constrain functions by precise states, and emulate dependent behavior for state machines, refined strings, and tagged sanitization without manual boilerplate.

AI-written summary · about

" chapters (5)

1. 0:00Start
2. 8:11THE SINGLETON PATTERN
3. 8:43DOOR STATUS
4. 9:45IMPLICIT PASSING
5. 11:06SINGLETONS TO THE RESCUE

" related talks

• 01h 20mA Practical Introduction to Haskell GADTsRichard A. Eisenberg · LambdaConf 2015
• 49mIntroduction to Linear Type Systems and Linear HaskellRyan Orendorff, Daniel Hensley · LambdaConf 2018
• 59mRock Solid Haskell Services (Part 1)Roman Gonzalez · LambdaConf 2018
• 01h 00mType Theory Behind the Glasgow Haskell Compiler Internals (Part 5)Vitaly Bragilevsky · LambdaConf 2018
• 49mA Hands on Tutorial to Generic Programming in Haskell (Part 2)Alejandro Serrano Mena · LambdaConf 2018
• 01h 01mType Theory Behind the Glasgow Haskell Compiler Internals (Part 6)Vitaly Bragilevsky · LambdaConf 2018
• 49mType Theory Behind the Glasgow Haskell Compiler Internals (Part 2)Vitaly Bragilevsky · LambdaConf 2018
• 41mIdris: Practical Dependent Types with Practical ExamplesBrian McKenna · Strange Loop 2014