[ANN] 2nd release elm_playground (a game engine for beginners)

Learning
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It is my pleasure, again, to announce the second release of elm_playground, an OCaml package that allows you to easily create pictures, animations, and even video games in a portable way using an API that really simplifies how to view the computer and its devices (the screen, keyboard, and mouse). The library offers a native backend to run the games from a terminal and a web backend to run the games in your browser.

This is a port of the excellent Elm playground package
GitHub - evancz/elm-playground: Create pictures, animations, and games with Elm! · GitHub to OCaml.

You can install it via OPAM via

opam install elm_playground; opam install elm_playground_native.

The main changes are most of the bugs in the first release have been fixed (mostly by Claude Code), and that now the native and web backend are fully working on all the examples and games. Here is for instance how to play Tetris compiled by jsoo:

https://aryx.github.io/ocaml-elm-playground/games/Tetris.html

Here are a few examples of code using the library.

First a “picture” app:

(* from https://elm-lang.org/examples/picture *)
open Playground

let app =
  picture [
    rectangle brown 40. 200.
      |> move_down 80.;
    circle green 100.
      |> move_up 100.;
  ]

let main = Playground_platform.run_app app

example-picture
example-picture1244×1318 26.5 KB

Then an “animation” app:

(* from https://elm-lang.org/examples/animation *)
open Playground

let view time = [
    octagon darkGray 36.
      |> move_left 100.
      |> rotate (spin 3. time);
    octagon darkGray 36.
      |> move_right 100.
      |> rotate (spin 3. time);
    rectangle red 300. 80.
      |> move_up (wave 50. 54. 2. time)
      |> rotate (zigzag (-. 2.) 2. 8. time);
  ]

let app =
  animation view

let main = Playground_platform.run_app app

example-animation
example-animation1244×1318 24.3 KB

And finally a “game” app:

(* from https://elm-lang.org/examples/mouse *)
open Playground

let view _computer (x, y) = [ 
  square blue 40.
   |> move x y
 ]

let update computer (x, y) =
  (x +. to_x computer.keyboard, y +. to_y computer.keyboard)

let app = 
  game view update (0., 0.)

let main = Playground_platform.run_app app

example-keyboard
example-keyboard1244×1318 22.2 KB

Note that you can write more complex games. For example here is a screenshot of a toy tetris app:

game-tetris
game-tetris582×686 12.6 KB

For more information, follow the README at GitHub - aryx/ocaml-elm-playground: Port of the Elm playground package to OCaml to make pictures, animations, and even video games easily. · GitHub

See also the code of some classic examples and try them online thx to jsoo: index

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