A Look Ahead to Programming Languages in 2020

class Complex {
  double _r,_i;
 
  Complex(this._r,this._i);
  double get r => _r;
  double get i => _i;
  String toString() => "($r,$i)";
 
  Complex operator +(Complex other) => new Complex(r+other.r,i+other.i);
  Complex operator *(Complex other) =>
      new Complex(r*other.r-i*other.i,r*other.i+other.r*i);
  double abs() => r*r+i*i;
}
 
void main() {
  double start_x=-1.5;
  double start_y=-1.0;
  double step_x=0.03;
  double step_y=0.1;
 
  for(int y=0;y<20;y++) {
    String line="";
    for(int x=0;x<70;x++) {
      Complex c=new Complex(start_x+step_x*x,start_y+step_y*y);
      Complex z=new Complex(0.0, 0.0);
      for(int i=0;i<100;i++) {
        z=z*(z)+c;
        if(z.abs()>2) {
          break;
        }
      }
      line+=z.abs()>2 ? " " : "*";
    }
    print(line);
  }
}

defmodule Mandelbrot do
  def set do
    xsize = 59
    ysize = 21
    minIm = -1.0
    maxIm = 1.0
    minRe = -2.0
    maxRe = 1.0
    stepX = (maxRe - minRe) / xsize
    stepY = (maxIm - minIm) / ysize
    Enum.each(0..ysize, fn y ->
      im = minIm + stepY * y
      Enum.map(0..xsize, fn x ->
        re = minRe + stepX * x
        62 - loop(0, re, im, re, im, re*re+im*im)
      end) |> IO.puts
    end)
  end
 
  defp loop(n, _, _, _, _, _) when n>=30, do: n
  defp loop(n, _, _, _, _, v) when v>4.0, do: n-1
  defp loop(n, re, im, zr, zi, _) do
    a = zr * zr
    b = zi * zi
    loop(n+1, re, im, a-b+re, 2*zr*zi+im, a+b)
  end
end
 
Mandelbrot.set

package main
 
import (
    "fmt"
    "image"
    "image/color"
    "image/draw"
    "image/png"
    "math/cmplx"
    "os"
)
 
const (
    maxEsc = 100
    rMin   = -2.
    rMax   = .5
    iMin   = -1.
    iMax   = 1.
    width  = 750
    red    = 230
    green  = 235
    blue   = 255
)
 
func mandelbrot(a complex128) float64 {
    i := 0
    for z := a; cmplx.Abs(z) < 2 && i < maxEsc; i++ {
        z = z*z + a
    }
    return float64(maxEsc-i) / maxEsc
}
 
func main() {
    scale := width / (rMax - rMin)
    height := int(scale * (iMax - iMin))
    bounds := image.Rect(0, 0, width, height)
    b := image.NewNRGBA(bounds)
    draw.Draw(b, bounds, image.NewUniform(color.Black), image.ZP, draw.Src)
    for x := 0; x < width; x++ {
        for y := 0; y < height; y++ {
            fEsc := mandelbrot(complex(
                float64(x)/scale+rMin,
                float64(y)/scale+iMin))
            b.Set(x, y, color.NRGBA{uint8(red * fEsc),
                uint8(green * fEsc), uint8(blue * fEsc), 255})
 
        }
    }
    f, err := os.Create("mandelbrot.png")
    if err != nil {
        fmt.Println(err)
        return
    }
    if err = png.Encode(f, b); err != nil {
        fmt.Println(err)
    }
    if err = f.Close(); err != nil {
        fmt.Println(err)
    }
}

using Images
 
@inline function hsv2rgb(h, s, v)
    const c = v * s
    const x = c * (1 - abs(((h/60) % 2) - 1))
    const m = v - c
 
    const r,g,b =
        if h < 60
            (c, x, 0)
        elseif h < 120
            (x, c, 0)
        elseif h < 180
            (0, c, x)
        elseif h < 240
            (0, x, c)
        elseif h < 300
            (x, 0, c)
        else
            (c, 0, x)
        end
 
    (r + m), (b + m), (g + m)
end
 
function mandelbrot()
 
    const w, h = 1000, 1000
 
    const zoom  = 0.5
    const moveX = 0
    const moveY = 0
 
    const img = Array{RGB{Float64}}(h, w)
    const maxIter = 30
 
    for x in 1:w
        for y in 1:h
            i = maxIter
            const c = Complex(
                (2*x - w) / (w * zoom) + moveX,
                (2*y - h) / (h * zoom) + moveY
            )
            z = c
            while abs(z) < 2 && (i -= 1) > 0
                z = z^2 + c
            end
            const r,g,b = hsv2rgb(i / maxIter * 360, 1, i / maxIter)
            img[y,x] = RGB{Float64}(r, g, b)
        end
    end
 
    save("mandelbrot_set.png", img)
end
 
mandelbrot()

import java.awt.Graphics
import java.awt.image.BufferedImage
import javax.swing.JFrame
 
class Mandelbrot: JFrame("Mandelbrot Set") {
    companion object {
        private const val MAX_ITER = 570
        private const val ZOOM = 150.0
    }
 
    private val img: BufferedImage
 
    init {
        setBounds(100, 100, 800, 600)
        isResizable = false
        defaultCloseOperation = EXIT_ON_CLOSE
        img = BufferedImage(width, height, BufferedImage.TYPE_INT_RGB)
        for (y in 0 until height) {
            for (x in 0 until width) {
                var zx = 0.0
                var zy = 0.0
                val cX = (x - 400) / ZOOM
                val cY = (y - 300) / ZOOM
                var iter = MAX_ITER
                while (zx * zx + zy * zy < 4.0 && iter > 0) {
                    val tmp = zx * zx - zy * zy + cX
                    zy = 2.0 * zx * zy + cY
                    zx = tmp
                    iter--
                }
                img.setRGB(x, y, iter or (iter shl 7))
            }
        }
    }
 
    override fun paint(g: Graphics) {
        g.drawImage(img, 0, 0, this)
    }
}
 
fun main(args: Array<String>) {
    Mandelbrot().isVisible = true
}

local maxIterations = 250
local minX, maxX, minY, maxY = -2.5, 2.5, -2.5, 2.5
local miX, mxX, miY, mxY
function remap( x, t1, t2, s1, s2 )
    local f = ( x - t1 ) / ( t2 - t1 )
    local g = f * ( s2 - s1 ) + s1
    return g;
end
function drawMandelbrot()
    local pts, a, as, za, b, bs, zb, cnt, clr = {}
    for j = 0, hei - 1 do
        for i = 0, wid - 1 do
            a = remap( i, 0, wid, minX, maxX )
            b = remap( j, 0, hei, minY, maxY )
            cnt = 0; za = a; zb = b
            while( cnt < maxIterations ) do
                as = a * a - b * b; bs = 2 * a * b
                a = za + as; b = zb + bs
                if math.abs( a ) + math.abs( b ) > 16 then break end
                cnt = cnt + 1
            end
            if cnt == maxIterations then clr = 0
            else clr = remap( cnt, 0, maxIterations, 0, 255 )
            end
            pts[1] = { i, j, clr, clr, 0, 255 }
            love.graphics.points( pts )
        end
    end
end
function startFractal()
    love.graphics.setCanvas( canvas ); love.graphics.clear()
    love.graphics.setColor( 255, 255, 255 )
    drawMandelbrot(); love.graphics.setCanvas()
end
function love.load()
    wid, hei = love.graphics.getWidth(), love.graphics.getHeight()
    canvas = love.graphics.newCanvas( wid, hei )
    startFractal()
end
function love.mousepressed( x, y, button, istouch )
    if button ==  1 then
        startDrag = true; miX = x; miY = y
    else
        minX = -2.5; maxX = 2.5; minY = minX; maxY = maxX
        startFractal()
        startDrag = false
    end
end
function love.mousereleased( x, y, button, istouch )
    if startDrag then
        local l
        if x > miX then mxX = x
        else l = x; mxX = miX; miX = l
        end
        if y > miY then mxY = y
        else l = y; mxY = miY; miY = l
        end
        miX = remap( miX, 0, wid, minX, maxX ) 
        mxX = remap( mxX, 0, wid, minX, maxX )
        miY = remap( miY, 0, hei, minY, maxY ) 
        mxY = remap( mxY, 0, hei, minY, maxY )
        minX = miX; maxX = mxX; minY = miY; maxY = mxY
        startFractal()
    end
end
function love.draw()
    love.graphics.draw( canvas )
end

Object subclass: #FractalTree
    instanceVariableNames: ''
    classVariableNames: ''
    poolDictionaries: ''
    category: 'RosettaCode'

"Methods for FractalTree class"

tree: aPoint length: aLength angle: anAngle
    | p a |
 
    (aLength > 10) ifTrue: [
        p := Pen new.
        p up.
        p goto: aPoint.
        p turn: anAngle.
        p down.
        5 timesRepeat: [
            p go: aLength / 5.
            p turn: 5.
        ].
        a := anAngle - 30.
        3 timesRepeat: [
            self tree: p location length: aLength * 0.7 angle: a.
            a := a + 30.
        ]
    ].
 
draw
    Display restoreAfter: [
        Display fillWhite.      
        self tree: 700@700 length: 200 angle: 0.
    ]

"Execute"

FractalTree new draw.

extern crate image;
extern crate num_complex;
 
use std::fs::File;
use num_complex::Complex;
 
fn main() {
    let max_iterations = 256u16;
    let img_side = 800u32;
    let cxmin = -2f32;
    let cxmax = 1f32;
    let cymin = -1.5f32;
    let cymax = 1.5f32;
    let scalex = (cxmax - cxmin) / img_side as f32;
    let scaley = (cymax - cymin) / img_side as f32;
 
    // Create a new ImgBuf
    let mut imgbuf = image::ImageBuffer::new(img_side, img_side);
 
    // Calculate for each pixel
    for (x, y, pixel) in imgbuf.enumerate_pixels_mut() {
        let cx = cxmin + x as f32 * scalex;
        let cy = cymin + y as f32 * scaley;
 
        let c = Complex::new(cx, cy);
        let mut z = Complex::new(0f32, 0f32);
 
        let mut i = 0;
        for t in 0..max_iterations {
            if z.norm() > 2.0 {
                break;
            }
            z = z * z + c;
            i = t;
        }
 
        *pixel = image::Luma([i as u8]);
    }
 
    // Save image
    let fout = &mut File::create("fractal.png").unwrap();
    image::ImageLuma8(imgbuf).save(fout, image::PNG).unwrap();
}

// Set up canvas for drawing
var canvas: HTMLCanvasElement = document.createElement('canvas')
canvas.width = 600
canvas.height = 500
document.body.appendChild(canvas)
var ctx: CanvasRenderingContext2D = canvas.getContext('2d')
ctx.fillStyle = '#000'
ctx.lineWidth = 1
 
// constants
const degToRad: number = Math.PI / 180.0
const totalDepth: number = 9
 
/** Helper function that draws a line on the canvas */
function drawLine(x1: number, y1: number, x2: number, y2: number): void {
    ctx.moveTo(x1, y1)
    ctx.lineTo(x2, y2)
}
 
/** Draws a branch at the given point and angle and then calls itself twice */
function drawTree(x1: number, y1: number, angle: number, depth: number): void {
    if (depth !== 0) {
        let x2: number = x1 + (Math.cos(angle * degToRad) * depth * 10.0)
        let y2: number = y1 + (Math.sin(angle * degToRad) * depth * 10.0)
        drawLine(x1, y1, x2, y2)
        drawTree(x2, y2, angle - 20, depth - 1)
        drawTree(x2, y2, angle + 20, depth - 1)
    }
}
 
// actual drawing of tree
ctx.beginPath()
drawTree(300, 500, -90, totalDepth)
ctx.closePath()
ctx.stroke()