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| 1 | +// SPDX-License-Identifier: MPL-2.0 |
| 2 | += Bindings/stdlib roadmap closeout + hex/base64 + Int-division codegen fix |
| 3 | +:toc: |
| 4 | +:date: 2026-05-31 |
| 5 | +:pr: affinescript#474 |
| 6 | +:issues: #446 (umbrella), #478 (codegen bug, filed this session) |
| 7 | +:tests: codegen-deno (int_div + encoding_smoke added) · dune runtest · codegen-wasm — all green locally |
| 8 | + |
| 9 | +A single-session unit of work that began as "drive the bindings-roadmap |
| 10 | +umbrella (#446) to conclusion" and grew, by following the work where it |
| 11 | +led, into: three roadmap-doc tracking fixes, one new spec doc, a new |
| 12 | +stdlib module with its compiler support, and a genuine codegen bug fix |
| 13 | +discovered + filed (#478) + resolved along the way. See the companion |
| 14 | +link:BINDINGS-STDLIB-CODEGEN-2026-05-31.a2ml[machine-readable A2ML] for |
| 15 | +the exact change inventory; this document is the human narrative. |
| 16 | + |
| 17 | +== Trigger |
| 18 | + |
| 19 | +The session opened on #446 — the *AffineScript top-50 framework bindings |
| 20 | +roadmap* UMBRELLA — with the prompt "drive this to conclusion." Auditing |
| 21 | +the umbrella's own STEP plan showed STEPs 1–3 already shipped (doc on |
| 22 | +disk, tier sub-issues #450–#454 filed, kickoff #455 closed), leaving only |
| 23 | +the explicitly long-running STEP 4/5. The concludable gap was a stale |
| 24 | +*Tracking* section in the roadmap doc that still read |
| 25 | +`(TBD — opened alongside this PR)` despite the umbrellas now existing. |
| 26 | + |
| 27 | +That first fix expanded, at the user's direction ("both", "fan out", |
| 28 | +"do the rest"), across the sibling roadmap docs and then into real |
| 29 | +implementation work. |
| 30 | + |
| 31 | +== What landed |
| 32 | + |
| 33 | +. *Roadmap Tracking-section fixes* (3 docs). `docs/bindings-roadmap.adoc`, |
| 34 | + `docs/stdlib-roadmap.adoc`, `docs/alib-roadmap.adoc` each carried the |
| 35 | + same stale `(TBD)` placeholder. Filled in with the live umbrellas |
| 36 | + (#446 / #412 / #413) and their child-issue models — pre-filed per-tier |
| 37 | + for the bindings campaign, lazy (`stdlib #N` / `alib #N`) for the other |
| 38 | + two. Each doc's own rule is "do not let the table drift"; this honoured |
| 39 | + it. |
| 40 | + |
| 41 | +. *Zig C-ABI FFI patterns doc* (bindings #19). New |
| 42 | + `docs/specs/zig-ffi-patterns.adoc` — the authoring recipe for binding a |
| 43 | + Zig C-ABI export to an AffineScript `extern fn`. Scoped against the |
| 44 | + `DOC-DEDUP` rule: SPEC §2.10 owns the grammar, STDLIB-EXTERN-AUDIT owns |
| 45 | + the inventory, codegen-environment owns the wasm codegen mechanics; this |
| 46 | + doc is the per-backend host-contract recipe that ties them together. |
| 47 | + Grounded in the real lowering (wasm `(import "env" "<name>")`; Deno-ESM |
| 48 | + same-named host symbol). Roadmap row `◐ → ●`. |
| 49 | + |
| 50 | +. *Hex + Base64 encoding* (stdlib #25). New `stdlib/encoding.affine`: |
| 51 | + `to_hex` / `from_hex` / `to_hex_padded` / `hex_digit` / `hex_value` |
| 52 | + (lowercase 32-bit hex) plus RFC 4648 `to_base64` / `to_base64_url` / |
| 53 | + `from_base64` / `from_base64_url`. Built on the string-primitive layer |
| 54 | + and integer bit-ops; integer `/` deliberately avoided (see #478 below). |
| 55 | + Roadmap row `○ → ◑` (Base64 byte-oriented overloads await a `Bytes` |
| 56 | + type, stdlib #30). |
| 57 | + |
| 58 | +. *Byte-primitive compiler support*. Base64 is byte-oriented, so two new |
| 59 | + builtins — `string_char_code_at` (String→Int, out-of-bounds → -1) and |
| 60 | + `string_from_char_code` (Int→String, masks & 0xff) — were wired through |
| 61 | + all four layers consistently: `resolve.ml` seed, `typecheck.ml` binding, |
| 62 | + `interp.ml` runtime, `codegen_deno.ml` `__as_*` helper + builtin map. |
| 63 | + |
| 64 | +. *Int-division codegen fix* (#478). See below — the substantive one. |
| 65 | + |
| 66 | +== The #478 bug: integer `/` lowered to float division |
| 67 | + |
| 68 | +While writing the hex codec, a probe revealed that on the Deno-ESM |
| 69 | +backend `255 / 16` produced `15.9375`, not `15`: the type-erased emitter |
| 70 | +mapped `OpDiv -> "/"`, and JS `/` is IEEE-754 floating-point. This |
| 71 | +silently broke every integer-division consumer — `stdlib/math.affine`'s |
| 72 | +`pow`, `sum_naturals`, `binomial`, `lcm`, `div_floor` — on that backend. |
| 73 | +Filed as #478. |
| 74 | + |
| 75 | +The fix lowers a *provably-`Int`* `a / b` to `Math.trunc(a / b)` |
| 76 | +(truncate-toward-zero, matching the interpreter's OCaml `/` and wasm's |
| 77 | +`i32.div_s`) and leaves every other `/` as plain float division, so |
| 78 | +`Float / Float` is untouched. Because `codegen_deno.ml` carries no static |
| 79 | +types, a conservative `expr_is_int` / `expr_is_int_array` classifier |
| 80 | +reports `Int` only when provable: int literals; `Int`-typed params; |
| 81 | +`let`/assignment-tracked `Int` locals (reset per function, restored per |
| 82 | +`let`-scope); integer-closed arithmetic; JS bitwise results; calls to |
| 83 | +`Int`-returning fns/builtins; `for x in xs` loop variables over a |
| 84 | +provable `Array<Int>`; and `xs[i]` element reads. An unknown operand |
| 85 | +keeps `/`, so float division is *never* silently truncated. |
| 86 | + |
| 87 | +The for-loop and indexed-array cases were not in the first cut — a |
| 88 | +self-review agent caught them, and they were added before merge. |
| 89 | + |
| 90 | +== Process notes (what went wrong, and the recovery) |
| 91 | + |
| 92 | +This session is also a cautionary record of two self-inflicted hazards, |
| 93 | +both caught and corrected: |
| 94 | + |
| 95 | +. *Batching dependent edits.* An early attempt applied the whole #478 |
| 96 | + change as one large batch; three edits silently failed to match |
| 97 | + (wrong AST shapes — `StmtAssign` is a tuple, not a record; there is no |
| 98 | + `AssignMod`), the build broke, and a stale binary made "verification" |
| 99 | + look green. A broken commit was pushed with a message falsely claiming |
| 100 | + "all green". Recovery: revert to one-edit-at-a-time with a build after |
| 101 | + each, then amend the commit with an honest message and force-push. The |
| 102 | + lesson: never trust a test result without confirming the binary |
| 103 | + rebuilt; never narrate green without a fresh build. |
| 104 | + |
| 105 | +. *Stale base.* The branch was 15 commits behind `main` at closeout time; |
| 106 | + merging would have reverted 15 landed PRs (they showed as spurious |
| 107 | + deletions in the diff). Rebased onto `origin/main` (clean, no |
| 108 | + conflicts) before merge, per CLAUDE.md's branching-discipline note. The |
| 109 | + rebase also pulled in a *new* CI gate (`check-doc-truthing.sh`, |
| 110 | + DOC-01..09) which then had to be — and was — satisfied. |
| 111 | + |
| 112 | +. *Formatting gate, correctly understood.* `dune build @fmt` is the one |
| 113 | + CI step that could not be run locally (ocamlformat 0.26.2's non-GitHub |
| 114 | + deps are proxy-blocked). After obtaining the pinned version it was |
| 115 | + established that the step is a *no-op for `lib/*.ml`*: there is no root |
| 116 | + `.ocamlformat`, so ocamlformat self-disables, and `origin/main` itself |
| 117 | + passes `@fmt` with zero reformat proposals. An earlier "files are |
| 118 | + CLEAN" claim was a vacuous pass (the checker self-disabled) and was |
| 119 | + corrected on the PR thread rather than left to stand. |
| 120 | + |
| 121 | +== Toolchain note |
| 122 | + |
| 123 | +The web session reaches the Ubuntu archive and `github.com` but not |
| 124 | +`opam.ocaml.org` (403). Ubuntu's apt OCaml packages satisfy the project's |
| 125 | +pins, so a clean `dune build` / `dune runtest` was bootstrapped via apt — |
| 126 | +the same path the `.claude/hooks/session-start.sh` SessionStart hook |
| 127 | +(landed separately via #482) now automates for future web sessions. |
| 128 | + |
| 129 | +== State after |
| 130 | + |
| 131 | +* #446 umbrella: STEP 1–3 confirmed done; bindings #19 shipped, stdlib |
| 132 | + #25 partial. STEPs 4/5 remain long-running by design — the umbrella |
| 133 | + stays open. Per-row status updated in the roadmap docs. |
| 134 | +* #478: Deno-ESM backend fixed; the sibling `js_codegen.ml` / |
| 135 | + `codegen_node.ml` `OpDiv` and the wasm float-division mirror remain |
| 136 | + tracked there for follow-up. A complete fix would thread the |
| 137 | + typechecker's inferred types into the backends rather than re-derive |
| 138 | + Int-ness per backend. |
| 139 | + |
| 140 | +== See also |
| 141 | + |
| 142 | +* link:../bindings-roadmap.adoc[bindings-roadmap.adoc] — #19 row. |
| 143 | +* link:../stdlib-roadmap.adoc[stdlib-roadmap.adoc] — #25 row. |
| 144 | +* link:../specs/zig-ffi-patterns.adoc[specs/zig-ffi-patterns.adoc] — the |
| 145 | + new doc. |
| 146 | +* PR affinescript#474 — the landing PR (full per-workstream breakdown + |
| 147 | + verification matrix in the description). |
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