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Exploring Higher Order Functions in Programming

Learn the power of higher-order functions and how to use them effectively in your coding projects. Discover how functions can be treated as data and the concept of mapping and reducing elements in lists. Dive into real-world examples and applications of higher-order functions in solving social problems with data. Enhance your programming skills today!

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Exploring Higher Order Functions in Programming

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  1. The Beauty and Joy of ComputingLecture #18Higher Order Functions I Instructor: Sean Morris Data Hacking Social Problems A summer fellowship program at University of Chicago encourages students to use data to tackle social problems. RayidGhani, chief scientist for President Obama’s re-election campaign. http://bits.blogs.nytimes.com/2013/07/25/a-summer-of-data-hacking-social-problems/?partner=rss&emc=rss&_r=0

  2. Why use functions? (review) The power of generalization!

  3. But how general can we be? ? The power of generalization!

  4. Today • Functions as Data • Higher-Order Functions • Useful HOFs (you can build your own!) • map Reporter over List • Report a new list, every element E of Listbecoming Reporter(E) • keep items such that Predicate from List • Report a new list, keeping only elements Eof List if Predicate(E) • combine with Reporter over List • Combine all the elements of List with Reporter(E) • This is also known as “reduce” • Acronym example • keep  map  combine

  5. en.wikipedia.org/wiki/First-class_function Functions as Data … • Programming Languages(BYOB) treat functions as first-class citizens: • Assign to a variable • Pass the function as an argument to another function • Report(return) a function from another function • Store a function in a data structure(List!) – think Vee • Higher-Order Function: Function that takes functions

  6. combine with Reporter over List a b c d

  7. Peer Instruction What will this report • List -> scar, smat • List -> cars, mats • List -> mats, cars • cars, mats • mats, cars

  8. Peer Instruction What will this report • List -> 1, 2, 3, 4, 5 • List -> 1, 2, 3 • List -> 4, 5 • List -> 2, 4 • List -> 1, 3, 5

  9. Peer Instruction What will this report • List -> band wagon • List -> bandwagon • band wagon • wagon band • bandwagon

  10. Summary • Functions as data is one of the two (programming) big ideas in this course • It’s a beautiful example of the abstraction of the list iteration details • Google (and other companies) use this! • They use “map-reduce” (Image Credit: Simply Scheme by Brian Harvey & Matt Wright) (Credit: Geekologie)

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