typdd-dev

Develop the typdd Typst library — a BDD visualization package built on fletcher.

Architecture

Pipeline: parse → build → reduce → layout → render

File	Role	Key functions
`lib.typ`	Public API, adaptive spacing	`bdd()`, `bdd-from-json()`
`src/parse.typ`	Tokenizer + recursive descent parser	`tokenize()`, `parse()`, `collect-vars()`
`src/bdd.typ`	Shannon expansion, unique table, reduction	`build-bdd()`, `build()`, `reduce()`, `substitute()`
`src/layout.typ`	Sugiyama-inspired layered layout	`assign-positions()`
`src/render.typ`	Fletcher diagram generation	`render-bdd()` (uses `node()`, `edge()`)
`src/styles.typ`	Visual presets + shared layout constants	`get-style()`, `merge-style()`, `_shared-layout`
`src/order.typ`	Variable ordering heuristics	`dfs-order()`, `weight-order()`, `force-order()`
`src/abstract.typ`	Subtree collapsing, stats	`collapse-subtrees()`, `bdd-stats()`
`src/import.typ`	JSON interchange import	`import-json()`

MCP server (typdd-mcp/): TypeScript mirror of parser/BDD engine with tools/prompts.

Recipes

Task	Files to touch
New operator	`src/parse.typ` (tokenizer + grammar) → `src/bdd.typ` (evaluate + substitute) → `tests/parse/test.typ` + `tests/bdd/test.typ`
New style	`src/styles.typ` (spread `_shared-layout`, colors/strokes only) → `get-style()` match → `examples/styles.typ`
Layout fix	`src/layout.typ` (barycenter, overlap resolution, centering)
Render change	`src/render.typ` (fletcher `node()`/`edge()`, stroke/fill/bend)
New API param	`lib.typ` (add to `bdd()` sig + `_render-pipeline()`)
JSON import	`src/import.typ` → `tests/integration/test.typ`

Data Structures

AST nodes (from parser):

code

(kind: "var", name: "x1")
(kind: "const", value: true/false)
(kind: "not", child: ast)
(kind: "binop", op: "&"|"|"|"^"|"=>"|"~&"|"~|"|"~^", left: ast, right: ast)
(kind: "ite", cond: ast, then-branch: ast, else-branch: ast)

BDD structure: (nodes: array, root: int, order: array) where each node is (id: int, kind: "terminal", value: bool) or (id: int, kind: "variable", var: str, low: int, high: int).

Unique table key: "var:low-id:high-id" — ensures canonical BDD nodes.

Test

bash

make test       # 4 Typst (tytanic) + MCP (bun test)
make typst      # Typst tests only: tt run
make mcp        # MCP tests only: cd typdd-mcp && bun test
make examples   # Rebuild PNGs

Tests are compile-time asserts — if any #assert.eq(...) fails, compilation exits non-zero. BDD correctness is verified via truth-table oracle (enumerate all 2^n assignments).

Rules

•Styles: colors/strokes only, never layout dims (those live in _shared-layout)
•Typst conventions: kebab-case, /// doc comments, absolute imports (/src/...)
•AST keys: then-branch/else-branch (not then/else)
•State threading: parser and builder return (result: ..., pos: ...) / (node-id: ..., nodes: ..., next-id: ..., unique-table: ...)
•No forward declarations: parser uses single _parse(tokens, pos, level) with level parameter to select grammar rule
•Grammar precedence (low→high): => → |/~| → ^/~^ → &/~& → !