ocaml: phase 1 match/with + pattern parser (+9 tests, 113 total)

Patterns: wildcard, literal, var, ctor (nullary + arg, flattens tuple
args so Pair(a,b) -> (:pcon "Pair" PA PB)), tuple, list literal, cons
:: (right-assoc), unit. Match: leading | optional, (:match SCRUT
CLAUSES) with each clause (:case PAT BODY). Body parsed via parse-expr
because | is below level-1 binop precedence.

plans/ocaml-on-sx.md

@@ -133,8 +133,11 @@ SX CEK evaluator (both JS and OCaml hosts)
       via `ocaml-parse-program`. _(Pending: `type`/`module`/`exception`/`open`/
       `include` decls, `match`/`with`, `try`/`with`, `function`, record literals/
       updates, field access, sequences `;`, `and` mutually-recursive bindings.)_
-- [ ] **Patterns:** constructor, literal, variable, wildcard `_`, tuple, list cons `::`,
-      list literal, record, `as`, or-pattern `P1 | P2`, `when` guard.
+- [~] **Patterns:** constructor (nullary + with args, incl. flattened tuple
+      args `Pair (a, b)` → `(:pcon "Pair" PA PB)`), literal (int/string/char/
+      bool/unit), variable, wildcard `_`, tuple, list cons `::`, list literal.
+      _(Pending: record patterns, `as` binding, or-pattern `P1 | P2`, `when`
+      guard.)_
 - [ ] OCaml is **not** indentation-sensitive — no layout algorithm needed.
 - [ ] Tests in `lib/ocaml/tests/parse.sx` — 50+ round-trip parse tests.
 
@@ -311,6 +314,14 @@ the "mother tongue" closure: OCaml → SX → OCaml. This means:
 
 _Newest first._
 
+- 2026-05-07 Phase 1 — `match`/`with` + pattern parser. Patterns: wildcard,
+  literal, var, ctor (nullary + with arg, with tuple-arg flattening so
+  `Pair (a, b)` → `(:pcon "Pair" PA PB)`), tuple, list literal, cons `::`
+  (right-assoc), parens, unit. Match clauses: leading `|` optional, body
+  parsed via `parse-expr`. AST: `(:match SCRUT CLAUSES)` where each clause
+  is `(:case PAT BODY)`. 113/113 tests passing (+9). Note: parse-expr is
+  used for case bodies, so a trailing `| pat -> body` after a complex body
+  will be reached because `|` is not in the binop table for level 1.
 - 2026-05-07 Phase 1 — top-level program parser `ocaml-parse-program`. Parses
   a sequence of `let [rec] name params* = expr` decls and bare expressions
   separated by `;;`. Output `(:program DECLS)` with each decl one of `(:def …)`,