jesperdj

/*
 * Copyright 2015 Jesper de Jong
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software

jesperdj

// See StackOverflow: http://stackoverflow.com/questions/3201577/scala-how-to-define-a-structural-type-that-refers-to-itself/3223088#3223088

object Example {
    trait Multipliable[X] { def *(d: Double): X }

    trait Addable[X] { def +(x: X): X }

    trait Interpolable[X] extends Multipliable[X] with Addable[X]

    implicit def double2interpolable(d: Double): Interpolable[Double] = new Interpolable[Double] {

jesperdj

// See: http://www.scala-notes.org/2010/08/a-generic-interpolate-method-using-type-classes/

// Trait for types that can be multiplied with a T, resulting in an R
trait Multipliable[-T, +R] {
  def *(value: T): R
}

// Trait for types to which a T can be added, resulting in an R
trait Addable[-T, +R] {
  def +(value: T): R

jesperdj

// Randomly permutate an array - Fisher-Yates shuffle (see: http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle)
// This method can also take a custom swap method, which is useful for example for Latin hypercube sampling
def shuffle[@specialized(Double) T](array: Array[T], swap: (T, T) => (T, T) = { (a: T, b: T) => (b, a) }): Array[T] = {
  val random = new scala.util.Random

  for (n <- array.length - 1 to 0 by -1) {
    val k = random.nextInt(n + 1)
    val (a, b) = swap(array(k), array(n)); array(k) = a; array(n) = b
  }

jesperdj

/*
 * Copyright 2011 Jesper de Jong
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software

jesperdj

/*
 * Copyright 2014 Jesper de Jong
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software

jesperdj

-- FizzBuzz in Haskell
import Data.Maybe

fizz x = if x `mod` 3 == 0 then Just "Fizz" else Nothing
buzz x = if x `mod` 5 == 0 then Just "Buzz" else Nothing

ops = [fizz, buzz]

result = map (\x -> let s = concat (mapMaybe ($ x) ops) in if null s then show x else s) [1..100]

jesperdj

// Simple prime number utilities
object Primes {
  private val buffer = scala.collection.mutable.ArrayBuffer(2)

  // Given the primes ps, check if x is a prime by trial division
  private def check(ps: Traversable[Int])(x: Int) = {
    val limit = math.sqrt(x).ceil.toInt
    ps takeWhile { _ <= limit } forall { x % _ != 0 }
  }

jesperdj

/*
 * Copyright 2013 Jesper de Jong
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software

jesperdj

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.List;
import java.util.function.Supplier;
import java.util.stream.Collectors;

public final class Example<T> {
    public static final Example<Integer> INT = new Example<>(Integer.class, () -> 123);
    public static final Example<String> STR = new Example<>(String.class, () -> "Test");