Frontend

[WinstonHartnett]

What should the ECS process from start-to-finish look like? Something like:

import Recs

main = do
  run . build $ do
    parallel [ mySys1, mySys2 ]
    mySys3 `after` mySys1
    mySys4 `after` mySys4Cleanup

mySys1 =
  emap (read @(Velocity, Time) -&- write @Position)
       (do
         (MkPosition v, MkTime t) <- bag
         tag (MkPosition $ p + dT *^ v))

mySys2 =
  emap (write @(Particle, Kinetic))
       (do
         MkParticle t <- bag
         if t < 0
           then untag @(Particle, Kinetic)
           else tag (MkParticle $ t - dT)

mySys3 =
  -- 'edo' allows you to manually run queries, spawn/despawn/get/tag/untag specific entities
  -- 'emap' is an 'edo' wrapper that launches straight into an archetype traversal
  edo (write @Velocity -&- inherit mySys2)
      (forM_ [0..1000] (const (make $ MkVelocity 0.0)) >> mySys2)
...

[WinstonHartnett]

Because of #7, the type signature goes from:

mySys :: System ([reads here], [writes here]) m ()

to

mySys :: System [reads] [writes] [tags] commands m ()

which is a lot uglier (but necessary for performance?).

[WinstonHartnett]

Current query primitives:

select @w @s     Select for systems with 's' with permission 'w'
tags             Enable insertion/removal for
low              Enable arbitrary entity spawning/destruction

Some extra properties (TODO):

exclusive        Blocks all other systems from running