haskell: Phase 14 — record syntax in parser (con-rec AST node)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/haskell/parser.sx

@@ -1212,16 +1212,47 @@
             (not (hk-match? "conid" nil))
             (hk-err "expected constructor name"))
           (let
-            ((name (get (hk-advance!) "value")) (fields (list)))
-            (define
-              hk-cd-loop
-              (fn
-                ()
-                (when
-                  (hk-atype-start? (hk-peek))
-                  (do (append! fields (hk-parse-atype)) (hk-cd-loop)))))
-            (hk-cd-loop)
-            (list :con-def name fields))))
+            ((name (get (hk-advance!) "value")))
+            (cond
+              ((hk-match? "lbrace" nil)
+                (begin
+                  (hk-advance!)
+                  (let
+                    ((rec-fields (list)))
+                    (define
+                      hk-rec-loop
+                      (fn
+                        ()
+                        (when
+                          (hk-match? "varid" nil)
+                          (let
+                            ((fname (get (hk-advance!) "value")))
+                            (begin
+                              (hk-expect! "reservedop" "::")
+                              (let
+                                ((ftype (hk-parse-type)))
+                                (begin
+                                  (append! rec-fields (list fname ftype))
+                                  (when
+                                    (hk-match? "comma" nil)
+                                    (begin (hk-advance!) (hk-rec-loop))))))))))
+                    (hk-rec-loop)
+                    (hk-expect! "rbrace" nil)
+                    (list :con-rec name rec-fields))))
+              (:else
+                (let
+                  ((fields (list)))
+                  (define
+                    hk-cd-loop
+                    (fn
+                      ()
+                      (when
+                        (hk-atype-start? (hk-peek))
+                        (begin
+                          (append! fields (hk-parse-atype))
+                          (hk-cd-loop)))))
+                  (hk-cd-loop)
+                  (list :con-def name fields)))))))
       (define
         hk-parse-tvars
         (fn

plans/haskell-completeness.md

@@ -247,7 +247,7 @@ No OCaml changes are needed. The view type is fully representable as an SX dict.
 
 ### Phase 14 — Record syntax
 
-- [ ] Parser: extend `hk-parse-data` to recognise `{ field :: Type, … }`
+- [x] Parser: extend `hk-parse-data` to recognise `{ field :: Type, … }`
   constructor bodies. AST node: `(:con-rec CNAME [(FNAME TYPE) …])`.
 - [ ] Desugar: `:con-rec` → positional `:con-def` plus generated accessor
   functions `(\rec -> case rec of …)` for each field name.
@@ -313,6 +313,13 @@ No OCaml changes are needed. The view type is fully representable as an SX dict.
 
 _Newest first._
 
+**2026-05-07** — Phase 14 record parser: `data Foo = Foo { name :: T, … }`:
+- Extended `hk-parse-con-def` to peek for `{` after the constructor name; if
+  found, parse `varid :: type` pairs separated by commas, terminate with `}`,
+  return `(:con-rec name [(fname ftype) …])`. Positional constructors fall
+  through to the existing `:con-def` path. Verified record parses; no
+  regressions in parse.sx (43/43), parser-decls (24/24), deriving (15/15).
+
 **2026-05-07** — Phase 13 conformance: shapes.hs (5/5) → Phase 13 complete:
 - `class Shape` with a default `perimeter` (using a where-clause inside the
   default body), two instances `Square` / `Rect` — Square overrides