The spec's unwritten operators say so by name

error, find-restart and compute-restarts are named in spec-conditions.md and had
no case in parse.ml, so each fell through to Call and came back as unknown name
- the very shape the house rule exists to prevent, and the one that makes a
missing feature look like a typo.

Three message strings from the previous commit had their line continuations
collapsed into runs of spaces. Rewrapped; no change to what they say.

NEXT.md

@@ -25,7 +25,9 @@ already has the stack they would walk.
 Still open from §3, and each refused by name today: **restarts with
 parameters** (argument marshalling plus the runtime arity check), and
 `handler-case`, which §"What this does not settle" leaves open as possibly a
-macro over `handler-bind` plus a transfer.
+macro over `handler-bind` plus a transfer. `error`, `find-restart` and
+`compute-restarts` now refuse by name too — they used to fall through to a call
+and come back as *unknown name*, which is the house rule's own class of bug.
 
 Read SBCL for what restarts should *mean* and ignore how it moves control: it
 transfers with `block`/`return-from`, which §6 rules out.

lib/parse.ml

@@ -237,7 +237,9 @@ and form f mk (head : Form.t) (args : Form.t list) : Ast.expr =
         when cbody <> [] ->
         if ps <> [] then
           fail c
-            "a restart takes no parameters yet — spec-conditions.md §3 has              them, and they need argument marshalling and a runtime arity              check that this version does not do";
+            "a restart takes no parameters yet — spec-conditions.md §3 has \
+             them, and they need argument marshalling and a runtime arity \
+             check that this version does not do";
         { Ast.rname = n; rbody = List.map expr cbody; rloc = c.Form.loc }
       | _ -> fail c "a restart-case clause is (name [] body ...)"
     in
@@ -252,14 +254,22 @@ and form f mk (head : Form.t) (args : Form.t list) : Ast.expr =
        mk (Ast.InvokeRestart n)
      | [ _ ] ->
        fail f
-         "invoke-restart takes a quoted restart name, as in           (invoke-restart 'use-placeholder)"
+         "invoke-restart takes a quoted restart name, as in \
+          (invoke-restart 'use-placeholder)"
      | _ ->
        fail f
-         "a restart takes no arguments yet — spec-conditions.md §3 has them,           and they need argument marshalling and a runtime arity check that           this version does not do")
+         "a restart takes no arguments yet — spec-conditions.md §3 has them, \
+          and they need argument marshalling and a runtime arity check that \
+          this version does not do")
 
   (* Recognised, deliberately unimplemented. Rejected rather than left to fall
      through to Call, where they would parse and mean nothing. *)
   | Sym ("handler-case"
+        (* Named in the spec and not written yet, so each says so rather than
+           falling through to Call and coming back as an unknown name: [error]
+           is §2's diverging signal, and [find-restart] and [compute-restarts]
+           are §4's two ways to look at the stack without committing. *)
+        | "error" | "find-restart" | "compute-restarts"
         | "errdefer" | "with-allocator" | "loop" | "recur"
         | "defmacro" | "await" as name) ->
     fail f "%s is not implemented yet (see the build sequence in plan.org)" name

test/test_flan.ml

@@ -691,9 +691,17 @@ let () =
   rejects_check "invoke-restart inside a defer"
     "(defn f [] i32 (defer (invoke-restart 'skip)) 0)"
     ~needle:"not allowed inside a defer";
-  (* Still unimplemented, and still says so by name. *)
-  rejects_check "handler-case is still unimplemented"
-    "(defn f [] (handler-case 1))" ~needle:"not implemented yet";
+  (* Still unimplemented, and still says so by name — which is the point: an
+     operator the spec names and the compiler lacks must not fall through to a
+     call and come back as an unknown name. *)
+  List.iter
+    (fun (name, src) ->
+       rejects_check (name ^ " is still unimplemented") src
+         ~needle:"not implemented yet")
+    [ "handler-case",     "(defn f [] (handler-case 1))";
+      "error",            "(defn f [] (error 1))";
+      "find-restart",     "(defn f [] (find-restart 'skip))";
+      "compute-restarts", "(defn f [] (compute-restarts))" ];
 
   (* ── The acceptance program checks end to end ──────────────────── *)
   accepts "calc-me.flan type checks"