ocaml: phase 1 expression parser (+37 tests, 95 total) — consumes lib/guest/pratt.sx

Atoms (literals/var/con/unit/list), application (left-assoc), prefix - / not,
29-op precedence table via pratt-op-lookup (incl. keyword-spelled mod/land/
lor/lxor/lsl/lsr/asr), tuples, parens, if/then/else, fun, let, let rec
with function shorthand. AST follows Haskell-on-SX (:int / :op / :fun / etc).

plans/ocaml-on-sx.md

@@ -125,12 +125,13 @@ SX CEK evaluator (both JS and OCaml hosts)
       int/float literals (incl. hex, exponent, underscores), nested block
       comments `(* ... *)`. _(labels `~label:` / `?label:` and heredoc `{|...|}`
       deferred — surface tokens already work via `~`/`?` punct + `{`/`|` punct.)_
-- [ ] **Parser:** top-level `let`/`let rec`/`type`/`module`/`exception`/`open`/`include`
-      declarations; expressions: literals, identifiers, constructor application,
-      lambda, application (left-assoc), binary ops with precedence table,
-      `if`/`then`/`else`, `match`/`with`, `try`/`with`, `let`/`in`, `begin`/`end`,
-      `fun`/`function`, tuples, list literals, record literals/updates, field access,
-      sequences `;`, unit `()`.
+- [~] **Parser:** expressions: literals, identifiers, constructor application,
+      lambda, application (left-assoc), binary ops with precedence (29 ops via
+      `lib/guest/pratt.sx`), `if`/`then`/`else`, `let`/`in`, `let rec`,
+      `fun`/`->`, tuples, list literals, `begin`/`end`, unit `()`. _(Pending:
+      top-level `let`/`type`/`module`/`exception`/`open`/`include` decls,
+      `match`/`with`, `try`/`with`, `function`, record literals/updates,
+      field access, sequences `;`.)_
 - [ ] **Patterns:** constructor, literal, variable, wildcard `_`, tuple, list cons `::`,
       list literal, record, `as`, or-pattern `P1 | P2`, `when` guard.
 - [ ] OCaml is **not** indentation-sensitive — no layout algorithm needed.
@@ -309,6 +310,14 @@ the "mother tongue" closure: OCaml → SX → OCaml. This means:
 
 _Newest first._
 
+- 2026-05-07 Phase 1 — `lib/ocaml/parser.sx` expression parser consuming
+  `lib/guest/pratt.sx` for binop precedence (29 operators across 8 levels,
+  incl. keyword-spelled binops `mod`/`land`/`lor`/`lxor`/`lsl`/`lsr`/`asr`).
+  Atoms (literals + var/con/unit/list), application (left-assoc), prefix
+  `-`/`not`, tuples, parens, `if`/`then`/`else`, `fun x y -> body`,
+  `let`/`let rec` with function shorthand. AST shapes match Haskell-on-SX
+  conventions (`(:int N)` `(:op OP L R)` `(:fun PARAMS BODY)` etc.). Total
+  95/95 tests now passing via `lib/ocaml/test.sh`.
 - 2026-05-07 Phase 1 — `lib/ocaml/tokenizer.sx` consuming `lib/guest/lex.sx`
   via `prefix-rename`. Covers idents, ctors, 51 keywords, numbers (int / float
   / hex / exponent / underscored), strings (with escapes), chars (with escapes),