ESKEES script language

The full reference is available in Japanese for now. This page is an overview. Alpha: details may change without notice.

ESKEES script describes everything from "change the expression when clicked" to small games like Tetris and Patapata. It has a Lua-like syntax with blocks closed by end, and can be edited as blocks, text or a diagram in ESKEES Studio. The same script runs in test play, the Player, showcase and ESKEES Screen.

What a script looks like

Only five kinds of things can appear at the top level: var, save, function, class and on (triggers).

var score = 0 to 999999 save          -- a number shown on screen and saved
save record = { best = 0 }            -- the save-data layout

function add(a, b)                     -- a function (top level only)
  return a + b
end

class Bird                             -- an actor class (the part named Bird)
  vy = 0
  function update(dt)
    self.y += self.vy * dt
  end
end

on press face                          -- a trigger
  score = add(score, 1)
end

Triggers

on start (once when opened), on frame (every frame, dt seconds), on every 1.5
on press / click / down / up for click areas and UI buttons (any for anywhere), on drag A to B, on tap Class
on key Space / on keyup (keyboard and gamepad names such as PadA)
on change var, on scene name

Statements

Control — if, switch, loop, while, repeat n … end, repeat … until, for i = 1, n do, for k, v in pairs(t) do, for each in Class, break, wait
Parts and animation — frame face = "smile", toggle, play, tween … to { … } in 0.25 ease "back-out"
Actors — spawn Class at x, y, destroy, self.x, touching Class, self:overlapping("Class"), spawn (expression) at x, y (class name from a table's part column), self.style = "Red" / spawn Class at x, y as Red (component styles)
Scenes, UI, sound — scene, scene Game fade 0.6 (fade to black and switch), on key Space in Game (a trigger that only fires in that scene and stops when you leave it), ui Panel show, ui Element hide / ui Element color "#ff4040" (one element inside a panel), say Text = "…", say Text = name (a variable's value), say Text = "Lv" .. lv or data.items.herb.name (expressions), sound, music, sound keys on a timeline clip (they play when play plays the clip), a component's own sound names (sound land / self:sound("land"))
Particles and shader values — effect Swirl param 1 = 3 (a GLSL effect's u_param), particles Star at x, y count 12 speed 160 life 0.8 gravity 600
Effects — effect Vignette = 0.8, effect Fade to 1 in 0.5 wait, effect Hit on self to 0 in 0.2 (screen and part effects by name)
Camera and stages — camera follow self, camera shake, stage "name", save.slot = 2 (switch save slots), tile.at, self:moveBy(dx, dy)
Scores — score total as Time lower sends a value to the leaderboard (see ESKEES Studio)

Differences from Lua

0 and the empty string are falsy; undefined variables are 0.
+= and -= exist; != works as well as ~=.
Functions only at the top level — no closures, no varargs, one return value.
Objects are class (actors) only; no metatables and no standard library such as os or io.
wait is a statement that pauses the script — no coroutines needed.

Naming

Names may be Japanese, but we recommend ASCII names for variables, functions, methods, classes and save data (score, addExp, class Enemy, save record). Full-width and half-width look-alikes otherwise create names that look identical but aren't. A class name is the name of its part, so parts that become classes should have ASCII names too. Text shown on screen can be in any language.