Hitchhiker's Guide to Functional Programming

on YouTube ↗51m

" summary

Starts from an imperative Java loop that computes the sum of squares of even numbers (result 220) and refactors it into small pure functions, showing iterate/filter/square/sum as separate composable expressions, then replaces loops with recursion and lifts patterns into higher-order combinators like flatMap/fold/map implemented with Java 8 lambdas. Demonstrates that Java 8 Streams reproduce the same pipeline, explains improved testability (no mocks), and warns about recursion/tail-call limits in JVM while recommending library-backed immutable structures for performance.

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" chapters (6)

1. 0:00Start
2. 3:30The Challenge
3. 31:46flatMap as fold
4. 35:03Beware Recursion
5. 40:46On Performance
6. 42:53On Testing...

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