Fixed step scheduler but its super Simple

FixedStepScheduler.lua

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+--!strict
+
+-- A simple fixed step system scheduler
+-- Fixed updates can happen multiple times per frame
+-- Variable updates will happen after all fixed updates complete
+
+local FIXED_DELTA = (1 / 60)
+local MAXIMUM_DELTA = (1 / 5) 
+
+export type System = {
+    --> variable delta_time update, used for rendering
+    --> blend used for interpolation of simulation state
+    update: ((delta_time: number, blend: number) -> ())?,
+    --> fixed delta_time update, used for simulation
+    fixed_update: ((delta_time: number, frame: number) -> ())?,
+}
+
+local function create(systems: {System}): (number) -> ()
+    local frame = 0
+    local accumulator = 0
+
+    return function(delta_time: number)
+        delta_time = math.min(delta_time, MAXIMUM_DELTA)
+        accumulator += delta_time
+    
+        local steps = 0
+        local previous_frame = frame
+    
+        if (accumulator > 0) then
+            --> typically done with a while accumulator >= fixed_rate but this way is 35x faster
+            steps = accumulator // FIXED_DELTA
+            frame += steps
+            accumulator -= (steps * FIXED_DELTA)
+        end
+
+        for step = 1, steps do
+            local step_frame = previous_frame + step
+            for _, system in systems do
+                if system.fixed_update == nil then
+                    continue
+                end
+
+                system.fixed_update(FIXED_DELTA, step_frame)
+            end
+        end
+        
+        local blend = accumulator / FIXED_DELTA
+        for _, system in systems do
+            if system.update == nil then
+                continue
+            end
+
+            system.update(delta_time, blend)
+        end
+    end
+end
+
+return create