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Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich

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Further reading 1

What can a language express, and what can it guarantee? →Factorial can be written without naming the function. That trick raises a harder question: if every program must terminate, can unrestricted recursion be allowed? Take that distinction into slides, libraries and language extensions.This video helps answer · Can anonymous functions recurse and still guarantee termination?

Caption notes

Starting with Church encodings and higher-order functions, Weirich derives recursion through self-application and arrives at a fixed-point combinator.

Original passages · 6
functions are the only data type. No integers, no strings,
Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich · ▶ 9:19–9:53
Recursion is no problem for it by doing this little trick
Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich · ▶ 36:21–36:38
the function y calculates the fixpoint of an improver function.
Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich · ▶ 46:27–47:02
it evaluates its arguments before it passes the arguments down into functions.
Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich · ▶ 47:59–48:48
calculates the fixpoint of an improver function
Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich · ▶ 46:31–46:42
you don't need the y combinator
Ruby Conf 12 - Y Not- Adventures in Functional Programming by Jim Weirich · ▶ 50:52–50:55

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