Why you should care about functional programming
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Why you should care about functional programming

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A introductory talk about the benefits of functional programming

A introductory talk about the benefits of functional programming

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    Why you should care about functional programming Why you should care about functional programming Presentation Transcript

    • Why you should care about Functional Programming Dhananjay Nene TechWeekend 5 December 18th, 2010
    • What is functional programming about ?
    • Functions = input + transformation + output
    • def add(x,y) : return x + ydef double(x) : return 2 * x
    • NO side effects
    • Unit Testing or Integration Testing when NO side effects ?
    • Benefit 1 : Testability
    • Benefit 2 : Easier Integration
    • All variables are final and are an alias to the result of a computation
    • A variable thus cannot have a different value at different points in time
    • Benefit 3 : Concurrency (no locking)
    • Constructs to easily parallelise operations
    • Benefit 4 : Ability to leverage multicores (if applicable)
    • Higher Order Functions :Functions which take functions as parameters
    • def repeat(f,x) : return f(x,x) double(x) OR repeat(add,x)
    • I like to imagine HOFs as policy injection
    • Brevity
    • public static <E extends Comparable<? super E>> List<E> quickSort(List<E> arr) { if (arr.size() <= 1) return arr; E pivot = arr.getFirst(); //This pivot can change to get faster results List<E> less = new LinkedList<E>(); List<E> pivotList = new LinkedList<E>(); List<E> more = new LinkedList<E>(); // Partition for (E i: arr) { if (i.compareTo(pivot) < 0) less.add(i); else if (i.compareTo(pivot) > 0) more.add(i); else pivotList.add(i); } // Recursively sort sublists less = quickSort(less); more = quickSort(more); // Concatenate results less.addAll(pivotList); less.addAll(more); return less;}
    • qsort1 :: Ord a => [a] -> [a]qsort1 [] = []qsort1 (p:xs) = qsort1 lesser ++ [p] ++ qsort1 greater where lesser = filter (< p) xs greater = filter (>= p) xs
    • Think different :
    • Recursion or Comprehensions instead of Loops
    • Pattern Matching instead of if conditions
    • Pattern Matching instead of State Machines
    • Information Transformation instead of sequence of tasks
    • Persistent Data Structures
    • Powerful concurrency constructs : Actors
    • Software Transactional Memory
    • At what cost ?
    • Retraining the brain: Fixed Cost (Remember OO?)
    • Actual development costs (variable) likely to be lesser. Could not find specific case studies.
    • Why ?
    • Programs are often smaller
    • Have a cleaner expression of intent (what instead of how)
    • Big ball of mud is harder to achieve with pure functions
    • Better future proofing in terms of being able to leverage multicore
    • Once you are able to read code written in functional style, its a lot more enjoyable
    • Faster, better, (cheaper?) and Enjoyable!