MEP-53 research notes
These twelve notes are the deep research that fed MEP-53 (Mochi-to-Rust transpiler). They are informative; the MEP body at /docs/mep/mep-0053 is normative. Each note is self-contained and can be read independently. Cross-references use [[note-slug]] markers.
Author: research pass for MEP-53 (Mochi-to-Rust transpiler). Date: 2026-05-29 (GMT+7).
| # | Title | Topic |
|---|---|---|
| 01 | Language surface | Mochi features mapped onto Rust 1.78+ lowering obligations |
| 02 | Design philosophy | Why Rust, why 1.78 floor, why single-thread runtime, why Box |
| 03 | Prior-art transpilers | bindgen / cbindgen, rust-bindgen, rapydscript-ng, rune, cretonne / Cranelift, gccrs, Polonius, mrustc, Rust-GPU, IL2Rust analogues, Embedded Rust, SwiftWasm comparison |
| 04 | Runtime building blocks | Rust stdlib, alloc crate, std::collections, std::net, panic::catch_unwind, no_std + alloc convention, the rejected tokio / reqwest / serde / sha2 alternatives |
| 05 | Codegen design | Rust source via rtree IR (not syn / quote), aotir reuse, the colour pass for borrow-and-clone elision, 4-space indent, stable item ordering |
| 06 | Type-system lowering | Mochi types onto i64 / f64 / String / Vec / HashMap / HashSet / struct / tagged enum / Box |
| 07 | Rust target and portability | Rust 1.78 / 1.95 matrix, host triples, cargo-zigbuild musl, wasm32-wasip1 (renamed from wasm32-wasi), no_std + alloc embedded, why no Polonius / gccrs / mrustc |
| 08 | Dataset pipeline | Query DSL via Iterator + itertools, BTreeMap for deterministic group-by, compile-time Datalog (semi-naive fixpoint) emitted as frozen Vec literals |
| 09 | Agents and streams | Agents as plain structs (no threads), single-thread Rc<RefCell |
| 10 | Build system | Cargo as canonical driver, deterministic Cargo.toml, SOURCE_DATE_EPOCH=0 + RUSTFLAGS=-C strip=symbols, cargo zigbuild for musl, wasmtime for wasm, the cffi/ sidecar + cc-rs build script |
| 11 | Testing gates | Per-phase Go test gates with vm3 oracle, byte-equal stdout diff, cargo check secondary gate, reproducibility SHA-256 gate, publish dry-run, embedded cargo check |
| 12 | Risks and alternatives | Risk register (LC_UUID macOS, generic-closure storage, wasm32 no-TCP, cc-rs detection, cassette drift, embedded surface gap) + rejected alternatives (tokio, reqwest, serde, sha2, Arc/Mutex, impl Fn, syn / quote, inlined runtime, no published crate) |
Each note's filename uses the NN-slug.md convention; the leading NN- is stripped by Docusaurus for the URL path, so cross-links inside the notes use the unprefixed slug (e.g. [[language-surface]]).
The companion MEP body lives at /docs/mep/mep-0053. Implementation tracking lives at /docs/implementation/0053/.