Lambda? You Keep Using that Letter

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" summary

Lambda calculus originates with Alonzo Church (1936) and proves undecidability while giving a syntax where everything is a function; numbers become Church numerals λf.λx.x that count repeated application and booleans choose between two branches. Implementations show surprises: Lisp and Scheme embody true lambdas from the 1960s/70s, actors turn out implementation-equivalent to closures, but mainstream languages differ — Java lambdas (2014) are syntactic sugar lacking free application and full type integration, C#/C++ partially support lambdas, and Excel LAMBDA (Dec 2020) actually provides full first-class lambdas.

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" chapters (8)

1. 0:00Introduction
2. 1:47Lambda calculus history
3. 10:37Lambda basics
4. 17:39Lambdas in languages
5. 27:13Lambda as unifier
6. 36:20Lambda in Excel
7. 41:38Church encoding
8. 48:15Conclusion

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