hiramekun

private def collectFirstSome[A, B](seq: Seq[A])(fn: A => Option[B]): Option[B] = {
    seq.collectFirst(Function.unlift(fn))
 }

hiramekun

import monocle.Monocle.toAppliedFocusOps

case class Country(name: String, code: String)

case class City(name: String, country: Country)

case class Address(number: Int, street: String, city: City)

case class Company(name: String, address: Address)

hiramekun

import cats.Monad
import scala.annotation.tailrec

object MyOption {
  implicit def optionMonad: Monad[MyOption] =
    new Monad[MyOption] {
      override def pure[A](x: A): MyOption[A] = MySome(x)

      override def flatMap[A, B](fa: MyOption[A])(f: A => MyOption[B]): MyOption[B] = fa match {
        case MySome(value) => f(value)

hiramekun

case class MyOrderedNum(value: Int) extends Ordered[MyOrderedNum] {
  override def compare(that: MyOrderedNum): Int = {
    if (this.value < that.value) -1
    else if (that.value < this.value) 1
    else 0
  }
}

case class MyOrderingNum(value: Int)(implicit ord: Ordering[MyOrderingNum]) {
  def >(that: MyOrderingNum): Boolean = ord.compare(this, that) > 0

hiramekun

import akka.actor.{Actor, ActorSystem, Props}
object HelloWorld extends App {
  val system = ActorSystem("system")
  val ref = system.actorOf(Props[MyActor])
  ref ! "HelloWorld"
}

class MyActor extends Actor {
  override def receive: Receive =  {
    case msg => println(msg)

hiramekun

class Publication(val title: String)

class Book(title: String) extends Publication(title)

object Library {
  val books: Set[Book] = Set(new Book("Programming in Scala"), new Book("Walden"))

  def printBookList(info: Book => AnyRef) = {
    for (book <- books) println(info(book))

hiramekun

環境

macOS Mojave

JDKのダウンロード

Java SE Development Kit 8u111を選択してダウンロードしてくる．
ファイル名はこれ．
jdk-8u111-macosx-x64.dmg
https://www.oracle.com/technetwork/java/javase/downloads/java-archive-javase8-2177648.html

パスを通す

環境変数として以下の二つを設定する．（ここは人によって違う．）

hiramekun

def draw_contour(target):
    n = 100
    x = np.linspace(-5, 5, n)
    y = np.linspace(-5, 5, n)
    X, Y = np.meshgrid(x, y)
    Z = target([X, Y])

    plt.gca().set_aspect('equal')
    plt.contour(X, Y, Z, levels=np.linspace(0, 200, 15))

hiramekun

#include <stdio.h>
#include <stdlib.h>

main() {
	char *a = malloc(1000);
	char *b = malloc(1000);
	char *c = malloc(1000);
	char *d = malloc(1000);
	printf("a:%lu\n", a);
	printf("b:%lu\n", b);

hiramekun

import matplotlib.pyplot as plt
%matplotlib inline
plt.rcParams['figure.figsize'] = (15.0, 15.0)