kmizu

def mul(x, y) = x _*_ y
mul(
  [1 2 3],
  [4
   5
   6]) // 32

kmizu

$ java -jar target/scala-2.13/matlike.jar
> 1
value = 1
> 23
value = 23
> [1 2 3; 4 5 6]
value =
[
  1 2 3
  4 5 6

kmizu

case class Add(l: Tree, r: Tree) extends Tree
case class Sub(l: Tree, r: Tree) extends Tree
case class Mul(l: Tree, r: Tree) extends Tree
case class Div(l: Tree, r: Tree) extends Tree
case class Num(v: Int) extends Tree

// switch ≒ match
def eval(tree: Tree): Int = tree match {
  case Add(l, r) =>  eval(l) + eval(r)
  case Sub(l, r) =>  eval(l) - eval(r)

kmizu

class Hello {
  def return100: Int = {
    for(i <- 1 to 1000) 
      if(i == 100) return 100
    0
  }
}

kmizu

import {
  com.pi4j.io.i2c.I2CBus;
  com.pi4j.io.i2c.I2Device;
  com.pi4j.io.i2c.I2CFactory;
  java.io.IOException;
}

def up(x: Byte): Int {
  return x;
}

kmizu

scalaVersion := "2.13.1"
name := "pi4r"
version := "0.0.1-SNAPSHOT"
libraryDependencies ++= Seq(
  "com.pi4j" % "pi4j-core" % "1.2",
  "com.pi4j" % "pi4j-device" % "1.2",
  "com.pi4j" % "pi4j-gpio-extension" % "1.2",
  "com.pi4j" % "pi4j-service" % "1.1",
  "com.pi4j" % "pi4j-native" % "1.2" pomOnly()
)

kmizu

public class Fact {
  public static int fact(int n) {
    if(i < 0) throw new IllegalArgumentException("n must be >= 0");
    int r = 1;
    for(int i = 1; i <= n; i++) {
      r *= i;
    } 
    return r;
  }
}

kmizu

import scala.reflect.macros.whitebox.Context
import scala.language.experimental.macros

object Macros {
  def test(body: Any*): Unit = macro testImpl
  def testImpl(c: Context)(body: c.Expr[Any]*) : c.Expr[Unit] = {
    import c.universe._
    for(expr <- body) {
      print("expr is ")
      expr.tree match {

kmizu

import scala.reflect.macros.whitebox.Context
import scala.language.experimental.macros

object Macros {
  def reverse(id: Any): Any = macro reverseImpl
  def reverseImpl(c: Context)(id: c.Expr[Any]) : c.Expr[Any] = {
    import c.universe._
    println(id)
    println(id.tree)
    println(id.getClass)

kmizu

import scala.reflect.macros.whitebox.Context
import scala.language.experimental.macros

object Macros {
  def reverse(id: Any): Any = macro reverseImpl
  def reverseImpl(c: Context)(id: c.Expr[Any]) : c.Expr[Any] = {
    import c.universe._
    val Ident(TermName(name)) = id.tree
    c.Expr[Any](Ident(TermName(name.reverse)))
  }