feat(codemode): add Set method parity

packages/codemode/interpreter-support.md

@@ -295,8 +295,8 @@ ultimate source of truth.
 - [x] Materialized `keys`, `values`, and `entries` arrays for Map and Set.
 - [x] Spread, `for...of`, `Array.from`, and `Object.fromEntries` integration.
 - [x] Map and Set values serialize to `{}` at host/JSON boundaries.
-- [ ] Set composition and relation methods: `union`, `intersection`, `difference`, `symmetricDifference`, `isSubsetOf`,
-      `isSupersetOf`, and `isDisjointFrom`.
+- [x] Set composition and relation methods: `union`, `intersection`, `difference`, `symmetricDifference`, `isSubsetOf`,
+      `isSupersetOf`, and `isDisjointFrom`, including supported Set-like operands.
 
 ## URL and URI helpers
 

packages/codemode/src/interpreter/methods.ts

@@ -103,7 +103,7 @@ export const invokeIntrinsic = <R>(
     // Native setters read the current time before argument coercion, whose callbacks may mutate the Date.
     const initialTime = target.time
     return Effect.map(
-      Effect.forEach(args.slice(0, argumentCount), (arg) => coerceDateSetterArgument(runner, arg, node), {
+      Effect.forEach(args.slice(0, argumentCount), (arg) => coerceNumericArgument(runner, arg, node), {
         concurrency: 1,
       }),
       (values) => invokeDateMethod(target, ref.name, values, node, initialTime),
@@ -127,7 +127,7 @@ export const invokeIntrinsic = <R>(
   throw new InterpreterRuntimeError(`Method '${ref.name}' is not available in CodeMode.`, node)
 }
 
-const coerceDateSetterArgument = <R>(
+const coerceNumericArgument = <R>(
   runner: CallbackRunner<R>,
   value: unknown,
   node: AstNode,
@@ -424,7 +424,7 @@ export const invokeGroupBy = <R>(
     throw new InterpreterRuntimeError(`${namespace}.groupBy expects an iterable collection.`, node).as("TypeError")
   }
   const apply = applyCollectionCallback(runner, args[1], `${namespace}.groupBy`, node)
-  const items = groupByItems(source)
+  const items = supportedIterableItems(source)
   if (items === undefined) {
     throw new InterpreterRuntimeError(`${namespace}.groupBy expects an iterable collection.`, node).as("TypeError")
   }
@@ -458,7 +458,7 @@ export const invokeGroupBy = <R>(
   })
 }
 
-const groupByItems = (source: unknown): Iterable<unknown> | undefined => {
+const supportedIterableItems = (source: unknown): Iterable<unknown> | undefined => {
   if (Array.isArray(source) || typeof source === "string") return source
   if (source instanceof CodeModeMap) return source.map.entries()
   if (source instanceof CodeModeSet) return source.set.values()
@@ -655,11 +655,140 @@ const invokeSetMethod = <R>(
         return undefined
       })
     }
+    case "union":
+    case "intersection":
+    case "difference":
+    case "symmetricDifference":
+    case "isSubsetOf":
+    case "isSupersetOf":
+    case "isDisjointFrom":
+      return invokeSetOperation(runner, target, name, args[0], node)
     default:
       throw new InterpreterRuntimeError(`Set method '${name}' is not available in CodeMode.`, node)
   }
 }
 
+const invokeSetOperation = <R>(
+  runner: CallbackRunner<R>,
+  target: CodeModeSet,
+  name: string,
+  source: unknown,
+  node: AstNode,
+): Effect.Effect<unknown, unknown, R> =>
+  Effect.gen(function* () {
+    const other = yield* loadSetRecord(runner, source, name, node)
+    if (name === "union") {
+      const result = copySet(target)
+      for (const item of yield* other.keys()) result.set.add(item)
+      return result
+    }
+    if (name === "intersection") {
+      const result = new CodeModeSet()
+      if (target.set.size <= other.size) {
+        for (const item of target.set.values()) {
+          if (yield* other.has(item)) result.set.add(item)
+        }
+        return result
+      }
+      for (const item of yield* other.keys()) {
+        if (target.set.has(item)) result.set.add(item)
+      }
+      return result
+    }
+    if (name === "difference") {
+      const result = copySet(target)
+      if (target.set.size <= other.size) {
+        for (const item of result.set.values()) {
+          if (yield* other.has(item)) result.set.delete(item)
+        }
+        return result
+      }
+      for (const item of yield* other.keys()) result.set.delete(item)
+      return result
+    }
+    if (name === "symmetricDifference") {
+      const result = copySet(target)
+      for (const item of yield* other.keys()) {
+        if (target.set.has(item)) result.set.delete(item)
+        else result.set.add(item)
+      }
+      return result
+    }
+    if (name === "isSubsetOf") {
+      if (target.set.size > other.size) return false
+      for (const item of target.set.values()) {
+        if (!(yield* other.has(item))) return false
+      }
+      return true
+    }
+    if (name === "isSupersetOf") {
+      if (target.set.size < other.size) return false
+      for (const item of yield* other.keys()) {
+        if (!target.set.has(item)) return false
+      }
+      return true
+    }
+    if (target.set.size <= other.size) {
+      for (const item of target.set.values()) {
+        if (yield* other.has(item)) return false
+      }
+      return true
+    }
+    for (const item of yield* other.keys()) {
+      if (target.set.has(item)) return false
+    }
+    return true
+  })
+
+const copySet = (source: CodeModeSet): CodeModeSet => {
+  const result = new CodeModeSet()
+  for (const item of source.set.values()) result.set.add(item)
+  return result
+}
+
+const loadSetRecord = <R>(runner: CallbackRunner<R>, source: unknown, name: string, node: AstNode) => {
+  if (source instanceof CodeModeSet) {
+    return Effect.succeed({
+      size: source.set.size,
+      has: (item: unknown) => Effect.succeed(source.set.has(item)),
+      keys: () => Effect.succeed(source.set.values()),
+    })
+  }
+  if (source instanceof CodeModeMap) {
+    return Effect.succeed({
+      size: source.map.size,
+      has: (item: unknown) => Effect.succeed(source.map.has(item)),
+      keys: () => Effect.succeed(source.map.keys()),
+    })
+  }
+  if (source === null || typeof source !== "object" || isCodeModeValue(source)) {
+    throw new InterpreterRuntimeError(`Set.${name} expects a Set-like object.`, node).as("TypeError")
+  }
+  const object = source as Record<string, unknown>
+  return Effect.gen(function* () {
+    const size = yield* coerceNumericArgument(runner, object.size, node)
+    if (Number.isNaN(size)) {
+      throw new InterpreterRuntimeError(`Set.${name} received a Set-like object with an invalid size.`, node).as(
+        "TypeError",
+      )
+    }
+    if (!isSupportedCallback(object.has) || !isSupportedCallback(object.keys)) {
+      throw new InterpreterRuntimeError(`Set.${name} expects callable 'has' and 'keys' methods.`, node).as("TypeError")
+    }
+    const has = object.has
+    const keys = object.keys
+    return {
+      size: Math.max(Math.trunc(size), 0),
+      has: (item: unknown) => Effect.map(runner.invokeCallable(has, [item], node), Boolean),
+      keys: () =>
+        Effect.flatMap(runner.invokeCallable(keys, [], node), (result) => {
+          if (Array.isArray(result)) return Effect.succeed(result)
+          throw new InterpreterRuntimeError(`Set.${name} expected 'keys' to return an iterator.`, node).as("TypeError")
+        }),
+    }
+  })
+}
+
 const invokeURLSearchParamsMethod = <R>(
   runner: CallbackRunner<R>,
   target: CodeModeURLSearchParams,

packages/codemode/src/stdlib/collections.ts

@@ -41,7 +41,23 @@ export const mapMethods = new Set(["get", "set", "has", "delete", "clear", "forE
 
 export const mapStatics = new Set(["groupBy"])
 
-export const setMethods = new Set(["add", "has", "delete", "clear", "forEach", "keys", "values", "entries"])
+export const setMethods = new Set([
+  "add",
+  "has",
+  "delete",
+  "clear",
+  "forEach",
+  "keys",
+  "values",
+  "entries",
+  "union",
+  "intersection",
+  "difference",
+  "symmetricDifference",
+  "isSubsetOf",
+  "isSupersetOf",
+  "isDisjointFrom",
+])
 
 export const spreadItems = (value: unknown): Array<unknown> | undefined => {
   if (Array.isArray(value)) return value