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Advanced Functional Programming with Scala - Notes

Copyright © 2017 Fantasyland Institute of Learning. All rights reserved.

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

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import io.Source
import scala.util.control.Breaks._

/**
 * Scala TicTacToe game without any side effects
 * 
 * Written in response to following post (which also contains task description):
 *   http://blog.tmorris.net/scala-exercise-with-types-and-abstraction/
 */
object TicTacToe {

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object TraversableWithStatistics {

  implicit class RichTraversable[A](collection: Traversable[A])(implicit val numeric : Numeric[A]) {

    private def pow2[C](x: C)(implicit num: Numeric[C]) = math.pow(num.toDouble(x), 2)

    private def sqrt[C](x: C)(implicit num: Numeric[C]) = math.sqrt(num.toDouble(x))

    def mean = {

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package com.jp;


import java.io.BufferedReader;
import java.io.FileReader;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.*;
import java.util.stream.IntStream;

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Category theory jargon cheat sheet

A primer/refresher on the category theory concepts that most commonly crop up in conversations about Scala or FP. (Because it's embarassing when I forget this stuff!)

I'll be assuming Scalaz imports in code samples, and some of the code may be pseudo-Scala.

Functor

A functor is something that supports map.

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# Prints the Total heap usage of Java process

jdk1.7.0/bin/jstat -gccapacity 9043  | tail -n 1 | awk '{ print $4, $5, $6, $10 }' | python -c "import sys; nums = [x.split(' ') for x in sys.stdin.readlines()]; print(str(sum([float(x) for x in nums[0]]) / 1024.0) + ' mb');"