Let's Lens - Part 1 of 5
summary
History and exercises focus on concrete implementations: Haskell code in the linked repos (requires GHC 7.8), exercises for Lets.GetSetLens and the optic/polymorphic versions, runnable doctests and QuickCheck examples, and a working library called lens. The talk gives actual definitions (the lens as getter+setter pair and the van Laarhoven representation), the three lens laws, worked modifier/set/get code, and how composing lens/prism/traversal produces the surprising, practical utilities that actually compile and test.
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chapters (6)
- 0:00Start
- 8:19Syntax
- 9:20Category Theory
- 12:48Polymorphic Update Problem
- 16:12The Get Set Law
- 45:56What Is a Lens
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