#hacker emblem

I wanted to blog about my work at Hacker School as and when it happened but having to part time on the side didn't give me as much time as I wanted. So now that Hacker School is over (:sad:) I am gonna write about all my time at Hackerschool one project at a time.

I am gonna start with the most fun and exciting projects I got to work on in some time - Implementing Conway's Game of life in Elm. See the glider pattern implemented here

Before I started this project, I had no introduction to Elm or any other functional programming language. So this was just an exercise in learning a new language. I paired with Alyssa & Cerek on this one and later after I finished Peter Seibel reviewed our work and made it infinitely better.

One of the most exciting thing about Elm or any functional language for that matter is the how terse the code is. 

Here is the whole code that took to build this:

import Dict import Graphics.Collage import Window import Debug -- Type alias for Grid and position to represent our game type Position = (Float, Float) type Grid = Dict.Dict (Float, Float) () newGrid: [Position] -> Grid newGrid ps = Dict.fromList (map (\p -> (p, ())) ps) liveCells: Grid -> [Position] liveCells g = Dict.keys g alive: Grid -> Position -> Bool alive g p = Dict.member p g validCell: Position > Bool validCell (x, y) = x >= 0 && y >= 0 neighbours: Position -> [Position] neighbours p = filter validCell (map (\d -> p `add` d) deltas) aliveNeighbours: Grid -> Position -> [Position] aliveNeighbours g p = filter (\p -> alive g p) (neighbours p) aliveInNextGeneration: Grid -> Position -> Bool aliveInNextGeneration g p = let liveNeighbors = length (aliveNeighbours g p) in (alive g p && liveNeighbors == 2) || liveNeighbors == 3 -- Constants. Sort of. gridSize = 500 cellSize = 50 gridDimension = gridSize/cellSize funColor = rgba 81 116 22 1.0 deltas = [(1, 0), (1, -1), (0, -1), (-1, -1), (-1, 0), (-1, 1), (0, 1), (1, 1)] glider = [(1, 0), (2, 1), (0, 2), (1, 2), (2, 2)] positions = concat (map (\y ->; map (\x ->; (x, y)) [0..gridDimension]) [0..gridDimension]) initialGrid = newGrid glider -- Tuple addition helper add: Position ->; Position ->; Position add (a1, b1) (a2, b2) = (a1 + a2, b1 + b2) -- Drawing helpers verticalLine : Float ->; Float ->; Path verticalLine height ordinate = path [ (ordinate, -height/2), (ordinate, height/2) ] horizontalLine : Float -> Float -> Path horizontalLine width abscissca = path [ (-width/2, abscissca), (width/2, abscissca) ] renderGrid : Float -> [Path] renderGrid size = let lines = map (\n ->; n * cellSize) [(-size/(2 * cellSize))..(size/(2 * cellSize))] in (map (verticalLine size) lines) ++ (map (horizontalLine size) lines) renderLiveCell : (Float, Float) -> Form renderLiveCell (x, y) = move (-gridSize/2 + (x * cellSize) + cellSize/2, gridSize/2 - (y * cellSize) - cellSize/2) (filled funColor (circle (cellSize/2.5))) renderLife: Grid -> [Form] renderLife g = map renderLiveCell (liveCells g) -- Evolve next generation from the current generation nextGeneration: Float -> Grid -> Grid nextGeneration pulse g = newGrid (filter (\p -> aliveInNextGeneration g p) positions) -- render render : Grid -> Int -> Int -> Element render g width height = container width height middle ( collage gridSize gridSize ( map (traced (solid black)) (renderGrid gridSize) ++ (renderLife g))) -- Render the animation now main = lift3 render (foldp (nextGeneration) initialGrid (fps 2)) Window.width Window.height

Pretty slick if I may say so myself!! The next target for this project is to create an editor for the grid so that one can create an initial state that can be triggered to evolve.