Reasoning about types and code
summary
A practical roadmap for reasoning about types and code: derive when a function is implementable (example: two signatures where F impossible, G implementable), prove flatMap cannot exist for certain business-shaped types and why Future + Either composition fails in Scala, rewrite code as algebraic type notation to expose an existential quantifier, and show that seemingly unprovable constructions like the selection monad transformer admit a five-line proof once the right symbolic notation is used.
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chapters (6)
- 0:00Introduction to reasoning
- 3:45Mathematical techniques in FP
- 9:53Notation for types and code
- 14:18Free monad equivalence proofs
- 19:04Advanced monad proofs
- 22:18Book resources and Q&A
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