ludic/examples
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feat(stdlib): add Query.* — ECS spatial queries over the reflection ABI (#42)
Completes the half of #24 that was explicitly deferred as blocked: entity-space
queries to sit alongside the grid-space Grid.*/pathfinding that shipped in
07e5a20. Query.* answers questions about the live entities that carry a
property, built directly on the EV2 reflection ABI (world_query_next/world_get):

  - Query.count(prop) -> int                 how many live entities carry prop
  - Query.first(prop) -> int                 the lowest-id bearer, or -1
  - Query.nearest(prop, pos, xf, yf, x, y)   the bearer closest to (x,y), or -1
  - Query.within(prop, pos, x, y, r, xf, yf) -> []int   every bearer within r

prop is a property id (World.prop_id); the spatial forms read a position from a
coordinate property `pos` at two int field ids (World.field_id), so `prop` can be
a discriminating tag distinct from the position component ("nearest Enemy"), or
the same id to query the coordinate component itself. Distances are exact squared
integers (no sqrt), ties break to the lower entity id, and `within` returns
entities in ascending id order — so every answer is deterministic and replay-safe.

The engine (runtime/native/query.ludic, ~55 lines of Ludic, C-free) is a linear
scan over the entity table — ample for the entity counts Ludic targets, the same
reasoning as the grid pathfinder's open set; a bucketed/quadtree index is a
future optimisation, not a correctness need. It is spliced on demand when the
parser sees Query.* (g_uses_query), which also force-emits the reflection ABI so
a Query program needs no @events of its own (previously the ABI required them).

examples/library/query.ludic asserts 18 cases over five entities at known
positions (count/first with a component filter, nearest with a separate tag vs
position property, within radii incl. r=0 and the empty-property case), wired
into x test (now 63 passed). Docs: a Query section + 4 per-symbol pages,
inventory/coverage green. Seed reseeded; the C-free bootstrap fixpoint holds.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-08-31 13:19:25 +03:00
..
ecs chore(repo): DX cleanup — categorise examples, text-diffable golden, build/ output (#27 #28 #30) 2026-08-30 18:54:21 +03:00
events chore(repo): DX cleanup — categorise examples, text-diffable golden, build/ output (#27 #28 #30) 2026-08-30 18:54:21 +03:00
games chore(repo): DX cleanup — categorise examples, text-diffable golden, build/ output (#27 #28 #30) 2026-08-30 18:54:21 +03:00
lang chore(repo): DX cleanup — categorise examples, text-diffable golden, build/ output (#27 #28 #30) 2026-08-30 18:54:21 +03:00
library feat(stdlib): add Query.* — ECS spatial queries over the reflection ABI (#42) 2026-08-31 13:19:25 +03:00
networking chore(repo): DX cleanup — categorise examples, text-diffable golden, build/ output (#27 #28 #30) 2026-08-30 18:54:21 +03:00
rendering chore(repo): DX cleanup — categorise examples, text-diffable golden, build/ output (#27 #28 #30) 2026-08-30 18:54:21 +03:00
README.md docs: move design/roadmap docs to the wiki, trim the repo root 2026-08-31 00:36:19 +03:00

Examples

A curated tour of Ludic, grouped by intent. Every example here is exercised by the test suite (bin/x test / bin/x selfhost-test), so nothing in this directory silently rots.

Run any program straight from the repository root (so assets/ resolves):

bin/x app examples/games/snake.ludic              # compile + open a real window
bin/x app examples/games/snake.ludic --headless   # render one frame to build/out.ppm
bin/ludic examples/lang/offline_rewards.ludic     # compile + run a plain program

games/ — complete, windowed games

Example What it shows
games/snake.ludic A full game from primitives: input, grid, growth, collision, score.
games/menu.ludic A retained-UI title screen — the UI declared as data.
games/chronorift.ludic A 2D co-op JRPG: overworld, dungeon, random encounters, turn battle, boss, save. The entry file imports the modules under games/chronorift/.

rendering/ — drawing primitives

Example What it shows
rendering/draw_prims.ludic The extended Screen.* primitives — line, circle, triangle, fill, sprite.

ecs/ — the entity-component world

Example What it shows
ecs/hello.ludic The smallest program that exercises the ECS pipeline.
ecs/world_get.ludic Reflection: read/write a component by name.
ecs/world_scan.ludic Reflection: scan the world and identify each entity.
ecs/world_query.ludic Reflection: iterate the world by property.
ecs/world_spawn.ludic Reflection: a mod spawns a fresh entity by model id.
ecs/world_mixed.ludic Reflection: get/set through real struct offsets.
ecs/world_dyn.ludic Reflection: register a brand-new component at runtime.

events/ — the event bus

Example What it shows
events/events.ludic EV0: the event-bus core — declare, emit, @On.
events/mod_events.ludic Two listeners on one event, driven from a mod.
events/cancel.ludic EV3: cancellable (decision) events.
events/recurse.ludic EV6: re-entrant emit is depth-bounded — no runaway cycle.
events/promote.ludic EV1: @Public promotes a lifecycle hook to a public event.
events/prop_events.ludic EV1 for properties: attach/detach events.
events/scene_events.ludic EV1 for scenes: on-enter / on-exit events.
events/program_events.ludic EV1 for the program scope: start/quit events.
events/layer_events.ludic EV1 for layers + a public layer's show/hide events.
events/scoped.ludic A despawned entity drops out of subsequent event work.

networking/ — deterministic multiplayer (N0–N6)

Each maps to a stage of the Networking design; all run over the compiler's built-in loopback transport with zero foreign code.

Example What it shows
networking/net_echo.ludic N0: the transport seam.
networking/net_snapshot.ludic N1: whole-world snapshot to a memory buffer.
networking/net_sync.ludic N2: @Sync replication codegen.
networking/net_owner.ludic N3: entity ownership.
networking/net_rpc.ludic N4: remote events / RPCs.
networking/net_roles.ludic N5: handler roles + the drivable sim.
networking/net_demo.ludic N6: a networked game end to end, in pure Ludic.
networking/net_rt.ludic A blessed server-authoritative replication runtime.

lang/ — language & standard-library tour

Example What it shows
lang/annotations.ludic The annotation-first style: @Queries / @Computed / @OnSpawn / @Handles.
lang/qdecl.ludic @Queries desugaring to the query system.
lang/lifecycle.ludic The whole game lifecycle as @-hooks, in firing order.
lang/detach.ludic Structural attach/detach + @OnAttach / @OnDetach.
lang/reason.ludic Reason-carrying teardown (@OnDespawn: Despawned vs Quit).
lang/toggle.ludic enable/disable at the three ECS scopes.
lang/scenes.ludic One active scene at a time, handlers grouped into layers.
lang/strings.ludic Strings as values: compare, join, interpolate, slice.
lang/rng_demo.ludic The Random.* extensions (value/int/sign).
lang/time_demo.ludic Time.frame / elapsed / delta.
lang/offline_rewards.ludic A worked idle-game example over the Time/Date/Duration stdlib.

library/ — building and linking a shared library

A how-to for compiling a .ludic module to a native .dylib/.so/.dll and linking a second program against it via extern fn:

bin/ludicc examples/library/combat.ludic --shared -o build/libcombat.dylib
bin/ludicc examples/library/arena.ludic  -o build/arena -Lbuild -lcombat
Example What it shows
library/combat.ludic Exported functions callable across the C ABI.
library/arena.ludic A program that links against the shared library.