Let's Lens - Part 4 of 5
summary
Exercises build concrete lenses in Haskell (requires GHC 7.8+) and walk from simple get/set to modern constructions, using the Lets.GetSetLens and Lets.Lens` modules and the real lens package. Code shows an alongside pattern, implementing a Map lens that does lookup then insert or delete, uses modify vs set, composes optics, and checks the lens laws. The repository examples compile against the course code and demonstrate the actual implementations and small runnable proofs rather than abstract promises.
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chapters (8)
- 0:00Introduction
- 3:29Lenses and isomorphisms
- 12:10Getter and setter functions
- 22:33Map lenses implementation
- 31:29Pattern recognition in composition
- 37:50Monadic patterns and laws
- 41:29Lens package and next steps
- 50:17Map modification exercise
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