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nescript/examples
Claude 1525922faa
examples: add 5 new programs covering match/loop/logic/bitwise/scanline
Fills the biggest feature-coverage gaps in the existing example set:

- match_demo.ne          — match statement over a Screen enum,
                           driving a title / playing / paused /
                           game-over flow with a debounced controller.
- loop_break_continue.ne — `loop { ... }` with `break` and `continue`,
                           scanning an enemy array for the first hit.
- logic_ops.ne           — keyword-based `and` / `or` / `not` gating
                           movement and scoring on alive/paused flags.
- bitwise_ops.ne         — packed status-byte flags with `&` / `|` /
                           `^` / `>>` plus a health-bar render loop.
- scanline_split.ne      — MMC3 `on scanline(120)` handler rewriting
                           the scroll register mid-frame for a
                           classic status-bar split.

All 14 examples (9 existing + 5 new) pass the jsnes smoke test
(`14/14 ROMs rendered successfully`) and still pass `cargo fmt`,
`cargo clippy -D warnings`, and `cargo test`.

Known limitations surfaced while authoring these examples, to be
fixed in follow-up commits:

1. Array-literal global initializers (`var xs: u8[4] = [1,2,3,4]`)
   are silently dropped by `lower_program` — `eval_const` returns
   None for `Expr::ArrayLiteral` and no synthetic per-element
   init code is emitted. Affects `arrays_and_functions`,
   `structs_enums_for`, `loop_break_continue`, and any future
   array-using example. Arrays effectively boot at all-zero.

2. `draw` inside a loop body reuses one static OAM slot —
   `next_oam_slot` increments at IR-codegen time rather than at
   runtime, so N iterations all write to the same 4-byte OAM
   entry. Affects `arrays_and_functions`, `structs_enums_for`,
   `bitwise_ops` (health pips), and any loop that wants to
   render per-iteration sprites.

Both bugs are latent and didn't surface until I tried to write
examples that exercise the relevant features — the existing
integration tests only check iNES header structure, and the
jsnes smoke test's "at least one sprite rendered" bar is
satisfied by one sprite even when several were intended.

https://claude.ai/code/session_014Z5y3Q9krLcAxYpZQJhZ5V
2026-04-12 19:05:18 +00:00
..
arrays_and_functions.ne Add README, LICENSE, examples, fix draw parser lookahead 2026-04-12 00:38:19 +00:00
bitwise_ops.ne examples: add 5 new programs covering match/loop/logic/bitwise/scanline 2026-04-12 19:05:18 +00:00
bouncing_ball.ne Add example builds to CI, document sprite name behavior 2026-04-11 22:55:43 +00:00
coin_cavern.ne M2: Wire IR pipeline, add Coin Cavern example and integration tests 2026-04-11 23:34:35 +00:00
hello_sprite.ne Add example builds to CI, document sprite name behavior 2026-04-11 22:55:43 +00:00
inline_asm_demo.ne examples: inline_asm_demo.ne 2026-04-12 18:02:59 +00:00
logic_ops.ne examples: add 5 new programs covering match/loop/logic/bitwise/scanline 2026-04-12 19:05:18 +00:00
loop_break_continue.ne examples: add 5 new programs covering match/loop/logic/bitwise/scanline 2026-04-12 19:05:18 +00:00
match_demo.ne examples: add 5 new programs covering match/loop/logic/bitwise/scanline 2026-04-12 19:05:18 +00:00
mmc1_banked.ne Add README, LICENSE, examples, fix draw parser lookahead 2026-04-12 00:38:19 +00:00
README.md Add README, LICENSE, examples, fix draw parser lookahead 2026-04-12 00:38:19 +00:00
scanline_split.ne examples: add 5 new programs covering match/loop/logic/bitwise/scanline 2026-04-12 19:05:18 +00:00
sprites_and_palettes.ne Add README, LICENSE, examples, fix draw parser lookahead 2026-04-12 00:38:19 +00:00
state_machine.ne Add README, LICENSE, examples, fix draw parser lookahead 2026-04-12 00:38:19 +00:00
structs_enums_for.ne Language: struct literals 2026-04-12 17:15:57 +00:00

NEScript Examples

Quick Start

# Build the compiler
cargo build --release

# Compile all examples
for f in examples/*.ne; do cargo run -- build "$f"; done

# Or compile one
cargo run -- build examples/hello_sprite.ne

Open any .nes file in an NES emulator (Mesen, FCEUX, etc.)

Examples

File Features Description
hello_sprite.ne input, draw Move a sprite with the d-pad
bouncing_ball.ne if/else, variables Auto-bouncing sprite with edge detection
coin_cavern.ne states, functions, constants 3-state game with gravity and coin collection
arrays_and_functions.ne arrays, functions, while Enemy array with collision detection
state_machine.ne on enter/exit, transitions Multi-state flow with timers
sprites_and_palettes.ne sprites, palettes, scroll, cast Inline CHR data, palette switching, type casting
mmc1_banked.ne MMC1, banks, multiply Banked mapper with software multiply

Emulator Controls

NES Button Typical Key
D-pad Arrow keys
A Z
B X
Start Enter
Select Right Shift

About Sprites

Sprite names in draw Player at: (x, y) are parsed and recorded in the AST. You can define sprites with inline CHR tile data:

sprite Player {
    chr: [0x3C, 0x42, 0x81, 0x81, 0x81, 0x81, 0x42, 0x3C,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
}

If no matching sprite declaration exists, the draw uses the built-in default tile (a smiley face). See sprites_and_palettes.ne for a full example.

Compiler Commands

# Compile to ROM
cargo run -- build game.ne

# Custom output path
cargo run -- build game.ne --output my_game.nes

# Type-check only
cargo run -- check game.ne

# View generated 6502 assembly
cargo run -- build game.ne --asm-dump

# Debug mode
cargo run -- build game.ne --debug