ECS.hs

-- | Aztecs is a type-safe and friendly ECS for games and more.
--
-- An ECS is a modern approach to organizing your application state as a database,
-- providing patterns for data-oriented design and parallel processing.
--
-- The ECS architecture is composed of three main concepts:
--
-- === Entities
-- An entity is an object comprised of zero or more components.
-- In Aztecs, entities are represented by their `EntityID`, a unique identifier.
--
-- === Components
-- A `Component` holds the data for a particular aspect of an entity.
-- For example, a zombie entity might have a @Health@ and a @Transform@ component.
--
-- > newtype Position = Position Int deriving (Show)
-- > instance Component Position
-- >
-- > newtype Velocity = Velocity Int deriving (Show)
-- > instance Component Velocity
--
-- === Systems
-- A `System` is a pipeline that processes entities and their components.
-- Systems in Aztecs either run in sequence or in parallel automatically based on the components they access.
--
-- Systems can access game state in two ways:
--
-- ==== Access
-- An `Access` can be queued for full access to the `World`, after a system is complete.
-- `Access` allows for spawning, inserting, and removing components.
--
-- > setup :: System  () ()
-- > setup = S.queue . const . A.spawn_ $ bundle (Position 0) <> bundle (Velocity 1)
--
-- ==== Queries
-- A `Query` can read and write matching components.
--
-- > move :: System  () ()
-- > move =
-- >  S.map
-- >    ( proc () -> do
-- >        Velocity v <- Q.query -< ()
-- >        Position p <- Q.query -< ()
-- >        Q.set -< Position $ p + v
-- >    )
-- >    >>> S.run print
--
-- Finally, systems can be run on a `World` to produce a result.
--
-- > main :: IO ()
-- > main = runSystem_ $ setup >>> S.forever move
module Aztecs.ECS
  ( module Aztecs.ECS.Access,
    module Aztecs.ECS.System,
    Bundle,
    BundleT,
    bundle,
    DynamicBundle,
    MonoidDynamicBundle (..),
    Component (..),
    EntityID,
    Query,
    query,
    queryMaybe,
    queryMap,
    queryMapM,
    queryMapWith,
    queryMapWith_,
    queryMapWithM,
    DynamicQueryF,
    QueryFilter,
    with,
    without,
    World,

    -- * Events
    Event,
    OnInsert (..),
    OnChange (..),
    OnRemove (..),

    -- * Observers
    Observer,
    observer,
    observerFor,
    observerGlobal,
  )
where

import Aztecs.ECS.Access
import Aztecs.ECS.Component (Component (..))
import Aztecs.ECS.Entity (EntityID)
import Aztecs.ECS.Event (Event, OnChange (..), OnInsert (..), OnRemove (..))
import Aztecs.ECS.Observer
  ( Observer (..),
    observer,
    observerFor,
    observerGlobal,
  )
import Aztecs.ECS.Query
  ( DynamicQueryF,
    Query,
    QueryFilter,
    query,
    queryMap,
    queryMapM,
    queryMapWith,
    queryMapWithM,
    queryMapWith_,
    queryMaybe,
    with,
    without,
  )
import Aztecs.ECS.System
import Aztecs.ECS.World (World)
import Aztecs.ECS.World.Bundle (Bundle, BundleT, bundle)
import Aztecs.ECS.World.Bundle.Dynamic (DynamicBundle, MonoidDynamicBundle (..))