bs testbed

Keys

Ctrl+Enter: Load the file live. main restarts; bullets in flight keep going.
Alt+Enter: Evaluate the form under the cursor, or the selection.
Ctrl+Shift+Enter: Start over with a fresh VM.
Ctrl+Shift+H: Hide or show the code.
Alt+P: Pause or play.
Alt+. and Alt+,: Step one tick forward or back.
F: Fullscreen, when you're not typing.
Ctrl+S, share: Copy a link that opens this script in this scene.
Ctrl+Shift+S: The same link in plain ASCII, for places that mangle Unicode.
download: Save the code as a .bs file.
Drop a .bs file: Open it from your computer.

defn def fn: (defn ring [n] …), (def n 3), (fn [] …)
let if when cond do and or: The usual. Values never change.
dotimes forever loop recur: (dotimes [i n] …), (loop [a 0] (recur …))
wait wait-until: Pause the script. (wait 0.5) is half a tick.
par race until: Run forms together. race and until cancel the rest.
fire: (fire :dir d :speed s :kind 'k :run f), all optional.
vanish emit: Remove this actor. (emit 'name) tells the host.
change-speed change-dir: (change-speed 0 :over 40) tweens in the background.
turn accel: (turn rate :for n), (accel ax ay :over n)
aim heading speed x y age: Ask about this actor and the target.
last-dir last-speed rand rank: The last shot, (rand a b), difficulty.
+ - * / mod inc dec abs: Arithmetic.
min max floor ceil round trunc: Limits and rounding.
sqrt pow sin cos tan atan2: Degrees, with 0 along +x and counterclockwise.
lerp clamp < > = not= not: Blending and comparison.
input: Inputs: (input 'var1) to (input 'var8), set from the settings menu.

Field: W × 448 units, origin bottom-left, y up. W follows the window; stay relative to the emitter.
Angles: Degrees, 0 is +x (right), counterclockwise: 90 is up, 270 is down toward the player.
Speed: Units per tick, at 60 ticks a second.
main: Spawned at the enemy, as its kind. Ctrl+Enter respawns it; bullets in flight carry on.
(aim): Points at the player ship, which follows the mouse.
rank: The rank slider, 0 to 1.
(input 'var1): Up to var8, from the settings menu.
Culling: Actors more than 32 units outside the field are removed.
emit: Names you emit show in the console at the bottom.
More: lists every sprite; show each form at work.

Any symbol works as a kind. Unknown ones draw as 'bullet; 'emitter draws nothing. Click to insert.