🔀 Merge feature/tagged-union-boolean-nullish-tags into main

backlog.tasks

@@ -63,6 +63,7 @@ Matcher:
 ☐ when using a union type as a property, the current behavior of tagged union matcher is
     to pass never to handler parameters
     → new matcher function needed or can be fixed in tagged union matcher
+    ☐ optional discriminant (`{ type?: "x" }`) is the same hole: the boolean/nullish change now admits the `undefined` tag, so the factory accepts the key, but `Extract<T, Record<K, V>>` still passes `never` to both the `x` and `undefined` handlers
 
 Bugs:
 ✔ TS 7 LSP server logs `context canceled` on stderr at shutdown @done
@@ -72,8 +73,8 @@ Enhancements:
 ✔ Allow boolean literals in primitive union patterns (e.g. `true: () => "yes"`) @medium @done
     ✔ Are there other primitive types that should be supported in union patterns? (e.g. `bigint`, `symbol`) @medium @done
         → added boolean, null and undefined; rejected `symbol` (compile-time brand, nothing at runtime) and `bigint` (not a property key)
-☐ Allow boolean, null and undefined discriminant values in tagged-union patterns @medium
+✔ Allow boolean, null and undefined discriminant values in tagged-union patterns @medium @done
-    → needs the primitive-union matcher's `PatternKey` / `PatternParam` projection; see development/library.md § Tagged-union matcher
+    → moved the `PatternKey` / `PatternParam` projection to `matcher-shared.ts` and keyed the tagged-union handler map through it; see development/library.md § Tagged-union matcher
 
 Documentation:
 ☐ Bring README.md back to its previous form — synopsis and examples restored, in the correct place

development/library.md

@@ -97,22 +97,29 @@ Each factory is two overloads whose order is load-bearing:
 
 #### Decision (2026-09)
 
-`src/matcher-shared.ts` holds the four universe-agnostic pieces both matchers
+`src/matcher-shared.ts` holds the seven universe-agnostic pieces both matchers
-use: `UnaryFn`, `PatternReturns`, `RedundantFallback`, `HandlerMap`.
+use: `UnaryFn`, `PatternReturns`, `RedundantFallback`, `HandlerMap`, the shared
+`Matchable` universe, and the `PatternKey` / `PatternParam` key projection.
 
 #### Why
 
 - `RedundantFallback`'s property name is the diagnostic, so one definition
-  keeps the two matchers' message from drifting; the other three appear verbatim
+  keeps the two matchers' message from drifting; the other pieces appear
-  in both public signatures.
+  verbatim in both public signatures or are the same projection over each
+  matcher's universe.
+- **`Matchable` is one definition, not two.** The primitive-union matcher's
+  universe and the tagged-union matcher's allowed `Tag` values are the same set,
+  so aliasing them keeps the two matchers from drifting apart on what they
+  accept (`symbol`/`bigint` rejected once).
 
 #### Rejected
 
 - **A generic `Matcher<Universe>` over the interface pair, `Handlers`,
   `Fallback` and `MustBePartial`.** Each is built from its own universe
-  (`PatternKey`/`PatternParam` vs `Tags`/`MapTaggedUnion`); abstracting over the
+  (`Tags`/`MapTaggedUnion` vs the primitive values); abstracting over the
   F-bounded `Handled` constraint that makes the remainder work risks the
-  contextual typing it exists to preserve.
+  contextual typing it exists to preserve. `Matchable` and the `PatternKey` /
+  `PatternParam` projection are the pieces both universes genuinely share.
 
 ## Tagged-union matcher
 
@@ -152,15 +159,18 @@ The key is a separate call because `K` is inferred from its literal argument and
   assertion, the tagged twin of the primitive-union dispatch's `shape as string | number`.
 - **`MapTaggedUnion` distributes with `Extract`.** A duplicated tag yields a
   union of members instead of dropping one.
+- **A `boolean` / `null` / `undefined` tag goes through the shared
+  `PatternKey` / `PatternParam` projection.** `Discriminated` admits those tags
+  (they are in `Tag`), but they cannot key a mapped type, so the handler map is
+  keyed by the stringified form (`true` → `"true"`) and `PatternParam` inverts
+  it to recover the member. This is the same projection the primitive-union
+  matcher uses over its universe, which is why it lives in `matcher-shared.ts`.
 
 #### Known issue
 
-- Tags are `string | number` only. A `boolean` / `null` / `undefined`
-  discriminant (`{ ok: true } | { ok: false }`) is rejected by `Discriminated`,
-  because those values are not property keys; supporting them needs the
-  primitive-union matcher's `PatternKey` / `PatternParam` projection.
 - A member's tag must be unique across the union; two members with the same tag
-  collapse to a union under one handler.
+  collapse to a union under one handler. The same holds for a tag colliding with
+  its stringification (`true | "true"`) — see [README § Caveats](../README.md#caveats).
 
 ## Primitive universe
 
@@ -172,7 +182,9 @@ with `boolean` admitted as `true | false`.
 `boolean`/`null`/`undefined` are not property keys, so handler-map keys are a
 projection (`PatternKey`: each member stringified) and `PatternParam` inverts
 it, so callbacks receive the real member (`true`, not `"true"`). The popup
-offers `true`, `false`, `null`, `undefined` by name (verified over LSP).
+offers `true`, `false`, `null`, `undefined` by name (verified over LSP). The
+same projection is shared with the tagged-union matcher; see
+§ Tagged-union matcher.
 
 #### Why
 

src/matcher-shared.ts

@@ -8,6 +8,38 @@ import type { ValueOf } from "type-fest";
 // A handler: one universe member in, one return value out.
 export type UnaryFn<T, R> = (shape: T) => R;
 
+// The primitive universe a matcher can discriminate. The primitive-union matcher
+// uses it directly; the tagged-union matcher uses it as the set of allowed
+// discriminant (`Tag`) values. `boolean` is admitted as the pair `true | false`;
+// see README § Caveats for the unsupported members.
+export type Matchable = string | number | boolean | null | undefined;
+
+// `boolean`, `null` and `undefined` cannot be property keys, so a mapped type
+// over a universe that includes one keys each such member by its
+// stringification. `PatternParam` inverts that projection, so a handler callback
+// still receives the *real* member (`true`, not `"true"`). Both matchers use the
+// projection: the primitive-union matcher over its universe, the tagged-union
+// matcher over a discriminant property's values. See README § Caveats for the
+// limits.
+export type PatternKey<T> = T extends boolean
+    ? T extends true
+        ? "true"
+        : "false"
+    : T extends null
+      ? "null"
+      : T extends undefined
+        ? "undefined"
+        : T;
+export type PatternParam<K> = K extends "true"
+    ? true
+    : K extends "false"
+      ? false
+      : K extends "null"
+        ? null
+        : K extends "undefined"
+          ? undefined
+          : K;
+
 // `Extract` drops optional handlers (`undefined`) so `PatternReturns` also works
 // when `P`'s constraint has optional keys.
 export type PatternReturns<P> = ReturnType<

src/primitive-union.ts

@@ -2,38 +2,14 @@ import type { Exact } from "type-fest";
 
 import type {
     HandlerMap,
+    Matchable,
+    PatternKey,
+    PatternParam,
     PatternReturns,
     RedundantFallback,
     UnaryFn,
 } from "./matcher-shared.ts";
 
-// The primitive universe a matcher can discriminate. `boolean` is admitted as
-// the pair `true | false`; see README § Caveats for the unsupported members.
-type Matchable = string | number | boolean | null | undefined;
-
-// `boolean`, `null` and `undefined` cannot be property keys, so a mapped type
-// over the universe keys each non-key member by its stringification. `Param`
-// inverts that projection, so a handler callback still receives the *real*
-// member (`true`, not `"true"`) — see README § Caveats for the limits.
-type PatternKey<T> = T extends boolean
-    ? T extends true
-        ? "true"
-        : "false"
-    : T extends null
-      ? "null"
-      : T extends undefined
-        ? "undefined"
-        : T;
-type PatternParam<K> = K extends "true"
-    ? true
-    : K extends "false"
-      ? false
-      : K extends "null"
-        ? null
-        : K extends "undefined"
-          ? undefined
-          : K;
-
 type Handlers<T extends Matchable, R> = {
     [K in PatternKey<T>]: UnaryFn<PatternParam<K>, R>;
 };
@@ -64,11 +40,10 @@ type MustBePartial<T extends Matchable, Handled> =
 // so `Exact` restores it for the generic forms: a handler map can otherwise
 // carry keys outside `T`.
 
-// oxlint-disable typescript/unified-signatures
 // Strict returns: one common `R`. Overload order is load-bearing:
 //   #1 Handlers (first) -> the exhaustive form and the autocomplete popup
 //   #2 Fallback (last)  -> accepts a partial handler map plus a fallback
-interface MatcherStrict<T extends Matchable> {
+interface PrimitiveUnionMatcherStrict<T extends Matchable> {
     <R>(handlers: Handlers<T, R>): UnaryFn<T, R>;
     <
         R,
@@ -79,13 +54,11 @@ interface MatcherStrict<T extends Matchable> {
         fallback: Fallback<T, Handled, R>,
     ): UnaryFn<T, R>;
 }
-// oxlint-enable typescript/unified-signatures
 
 // Widened returns: the union of every handler's return type. `P` is inferred
 // from the whole handler map, whose closed constraint supplies the
 // contextual/autocomplete type.
-// oxlint-disable typescript/unified-signatures
+interface PrimitiveUnionMatcherWidening<T extends Matchable> {
-interface MatcherWidening<T extends Matchable> {
     <P extends Exact<Handlers<T, unknown>, P>>(
         handlers: P,
     ): UnaryFn<T, PatternReturns<P>>;
@@ -98,7 +71,6 @@ interface MatcherWidening<T extends Matchable> {
         fallback: Fallback<T, Handled, R>,
     ): UnaryFn<T, PatternReturns<Handled> | R>;
 }
-// oxlint-enable typescript/unified-signatures
 
 const dispatch =
     (handlers: HandlerMap, fallback?: UnaryFn<never, unknown>) =>
@@ -125,7 +97,7 @@ const dispatch =
 
 export const getPrimitiveUnionMatcher = <
     T extends Matchable,
->(): MatcherStrict<T> => dispatch;
+>(): PrimitiveUnionMatcherStrict<T> => dispatch;
 export const getPrimitiveUnionMatcherW = <
     T extends Matchable,
->(): MatcherWidening<T> => dispatch;
+>(): PrimitiveUnionMatcherWidening<T> => dispatch;

src/tagged-union.test.ts

@@ -100,6 +100,147 @@ test("getTaggedUnionMatcher: dispatches on numeric tags", () => {
     assert.equal(pick({ kind: 2, b: 20 }), 20);
 });
 
+test("getTaggedUnionMatcher: dispatches on boolean tags", () => {
+    // Arrange — a boolean discriminant is not a property key, so the handler
+    // map is keyed `true`/`false` and the callback still receives the boolean.
+    interface Ok {
+        readonly status: true;
+        readonly value: number;
+    }
+    interface Err {
+        readonly status: false;
+        readonly message: string;
+    }
+    type Result = Ok | Err;
+    const factory = getTaggedUnionMatcher<Result>()("status");
+
+    // Act
+    const pick = factory({
+        true: (s) => {
+            expectTypeOf(s).toEqualTypeOf<Ok>();
+            assert.equal(s.status, true);
+            return s.value;
+        },
+        false: (s) => {
+            expectTypeOf(s).toEqualTypeOf<Err>();
+            assert.equal(s.status, false);
+            return s.message.length;
+        },
+    });
+
+    // Assert
+    expectTypeOf(pick).toEqualTypeOf<(shape: Result) => number>();
+    assert.equal(pick({ status: true, value: 3 }), 3);
+    assert.equal(pick({ status: false, message: "hi" }), 2);
+});
+
+test("getTaggedUnionMatcher: dispatches on null and undefined tags", () => {
+    // Arrange
+    type Maybe =
+        | { readonly kind: null; readonly text: string }
+        | { readonly kind: undefined; readonly code: number };
+    const factory = getTaggedUnionMatcher<Maybe>()("kind");
+
+    // Act
+    const pick = factory({
+        null: (s) => {
+            expectTypeOf(s).toEqualTypeOf<{
+                readonly kind: null;
+                readonly text: string;
+            }>();
+            assert.equal(s.kind, null);
+            return s.text.length;
+        },
+        undefined: (s) => {
+            expectTypeOf(s).toEqualTypeOf<{
+                readonly kind: undefined;
+                readonly code: number;
+            }>();
+            assert.equal(s.kind, undefined);
+            return s.code;
+        },
+    });
+
+    // Assert
+    expectTypeOf(pick).toEqualTypeOf<(shape: Maybe) => number>();
+    assert.equal(pick({ kind: null, text: "hi" }), 2);
+    assert.equal(pick({ kind: undefined, code: 7 }), 7);
+});
+
+test("getTaggedUnionMatcher: a fallback receives unhandled boolean and nullish members", () => {
+    // Arrange
+    type Mixed =
+        | { readonly kind: "a"; readonly a: number }
+        | { readonly kind: true; readonly b: number }
+        | { readonly kind: false; readonly c: number }
+        | { readonly kind: null; readonly d: number };
+    const factory = getTaggedUnionMatcher<Mixed>()("kind");
+
+    // Act
+    const pick = factory({ a: () => 1 as const }, (s) => {
+        // The fallback sees the real members, not the projected keys.
+        expectTypeOf(s).toEqualTypeOf<
+            | { readonly kind: true; readonly b: number }
+            | { readonly kind: false; readonly c: number }
+            | { readonly kind: null; readonly d: number }
+        >();
+        // `true`/`false`/`null` are keyed as `"true"`/`"false"`/`"null"`,
+        // but the fallback still receives the boolean/null, not the string.
+        assert.ok(s.kind === true || s.kind === false || s.kind === null);
+        return 2 as const;
+    });
+
+    // Assert
+    expectTypeOf(pick).toEqualTypeOf<(shape: Mixed) => 1 | 2>();
+    assert.equal(pick({ kind: "a", a: 1 }), 1);
+    assert.equal(pick({ kind: true, b: 1 }), 2);
+    assert.equal(pick({ kind: false, c: 1 }), 2);
+    assert.equal(pick({ kind: null, d: 1 }), 2);
+});
+
+test("getTaggedUnionMatcherW: boolean and nullish tags widen to the union", () => {
+    // Arrange
+    type Maybe =
+        | { readonly kind: true; readonly a: number }
+        | { readonly kind: false; readonly b: number }
+        | { readonly kind: null; readonly c: number };
+    const factory = getTaggedUnionMatcherW<Maybe>()("kind");
+
+    // Act
+    const matcher = factory({
+        true: (s) => {
+            expectTypeOf(s).toEqualTypeOf<{
+                readonly kind: true;
+                readonly a: number;
+            }>();
+            assert.equal(s.kind, true);
+            return "yes" as const;
+        },
+        false: (s) => {
+            expectTypeOf(s).toEqualTypeOf<{
+                readonly kind: false;
+                readonly b: number;
+            }>();
+            assert.equal(s.kind, false);
+            return 0 as const;
+        },
+        null: (s) => {
+            expectTypeOf(s).toEqualTypeOf<{
+                readonly kind: null;
+                readonly c: number;
+            }>();
+            assert.equal(s.kind, null);
+            return null;
+        },
+    });
+
+    // Assert
+    expectTypeOf(matcher).toEqualTypeOf<(shape: Maybe) => "yes" | 0 | null>();
+    assert.equal(matcher({ kind: true, a: 1 }), "yes");
+    assert.equal(matcher({ kind: false, b: 1 }), 0);
+    assert.equal(matcher({ kind: null, c: 1 }), null);
+});
+
 // ============================================================================
 // API: getTaggedUnionMatcher — ❌ Exhaustive (fallback) / ✔️ ReturnsStrict
 // ============================================================================
@@ -260,6 +401,26 @@ test("getTaggedUnionMatcher factory rejects a non-discriminant key", () => {
     getTaggedUnionMatcher<Mixed>()("kind");
 });
 
+test("getTaggedUnionMatcher factory rejects non-exhaustive boolean and nullish maps", () => {
+    // Arrange
+    type Result =
+        | { readonly status: true; readonly a: number }
+        | { readonly status: false; readonly b: number };
+    type Maybe =
+        | { readonly status: null; readonly c: number }
+        | { readonly status: undefined; readonly d: number };
+    const resultFactory = getTaggedUnionMatcher<Result>()("status");
+    const maybeFactory = getTaggedUnionMatcher<Maybe>()("status");
+
+    // Act / Assert — the calls below must not compile
+    // @ts-expect-error only `true` is handled; `false` is not
+    resultFactory({ true: () => 1 });
+    // @ts-expect-error only `null` is handled; `undefined` is not
+    maybeFactory({ null: () => 1 });
+    // @ts-expect-error a fallback is redundant once both tags are handled
+    resultFactory({ true: () => 1, false: () => 2 }, () => 0);
+});
+
 test("getTaggedUnionMatcherW factory rejects patterns outside its contract", () => {
     // Arrange
     const factory = getTaggedUnionMatcherW<Shape>()("kind");
@@ -321,6 +482,8 @@ interface LabelsProbe {
     readonly factory: "getTaggedUnionMatcher" | "getTaggedUnionMatcherW";
     readonly body: string;
     readonly tail?: string;
+    readonly typeName?: string;
+    readonly typeSource?: string;
 }
 
 const labelsFor = ({
@@ -328,14 +491,16 @@ const labelsFor = ({
     factory,
     body,
     tail = "",
+    typeName = "Shape",
+    typeSource = SHAPE_SOURCE,
 }: LabelsProbe): Promise<readonly string[]> => {
     const session = new LspSession(REPO_ROOT);
     const target: CompletionTarget = {
         file: `src/__autocomplete_${name}.ts`,
         source: [
             `import { ${factory} } from "./index.ts";`,
-            SHAPE_SOURCE,
+            typeSource,
-            `const m = ${factory}<Shape>()("kind")({`,
+            `const m = ${factory}<${typeName}>()("kind")({`,
             body,
             `}${tail});`,
             "",
@@ -399,6 +564,29 @@ test("autocomplete: a fallback makes the remaining tags optional", () => {
     });
 });
 
+// `true`/`false`/`null`/`undefined` tags are not property keys, so the popup
+// must offer them by name through the `PatternKey` projection.
+const STATUS_SOURCE = `type Status = { kind: true; a: number } | { kind: false; b: number } | { kind: null; c: number } | { kind: undefined; d: number };`;
+
+test("autocomplete: boolean and nullish tags are offered by name", () => {
+    // Arrange
+    const name = "tagged_union_boolean_nullish";
+
+    // Act
+    const labels = labelsFor({
+        name,
+        factory: "getTaggedUnionMatcher",
+        typeName: "Status",
+        typeSource: STATUS_SOURCE,
+        body: "    /*COMPLETE*/",
+    });
+
+    // Assert
+    return labels.then((result) => {
+        assert.deepEqual([...result], ["false", "null", "true", "undefined"]);
+    });
+});
+
 // `Mixed` has two common keys, but `id`'s value is not a tag, so only `kind`
 // may serve as the discriminant.
 const MIXED_SOURCE = `type Mixed = { id: Date; kind: "a"; a: number } | { id: Date; kind: "b"; b: number };`;

src/tagged-union.ts

@@ -2,46 +2,53 @@ import type { Exact, UnknownRecord } from "type-fest";
 
 import type {
     HandlerMap,
+    Matchable,
+    PatternKey,
+    PatternParam,
     PatternReturns,
     RedundantFallback,
     UnaryFn,
 } from "./matcher-shared.ts";
 
-// A tagged union is discriminated by one property whose values are the tags.
+// A tagged union is discriminated by one property whose values are the tags (a
-// Only `string` and `number` tags can key a handler map: `symbol` has no
+// `Matchable`). `string` and `number` tags key a handler map directly;
-// literal syntax to write a handler under, and `bigint` is not a property key.
+// `boolean`, `null` and `undefined` are admitted too but are not property keys,
-type Tag = string | number;
+// so they go through the `PatternKey` projection. `symbol` has no literal syntax
+// to write a handler under, and `bigint` is not a property key.
 
 // The discriminant values of `T` under `K`. `Extract` keeps the finite literal
 // tags and leaves a widened `string`/`number` as itself, so an open universe
 // keeps an open fallback.
-type Tags<T extends object, K extends keyof T> = Extract<T[K], Tag>;
+type Tags<T extends object, K extends keyof T> = Extract<T[K], Matchable>;
 
 // The keys of `T` that can act as a discriminant. `getTaggedUnionMatcher<T>()`
 // accepts only these, so the factory rejects a key whose values are not tags.
 type Discriminated<T extends object> = {
-    [K in keyof T]: T[K] extends Tag ? K : never;
+    [K in keyof T]: T[K] extends Matchable ? K : never;
 }[keyof T];
 
 // The member(s) of `T` tagged `V`. `Extract` distributes over the union, so a
 // duplicated tag maps to a union of members rather than silently dropping one.
+// Keyed by `PatternKey`, so `boolean`/`null`/`undefined` tags can key a mapped
+// type; `PatternParam` inverts the projection to recover the member.
 type MapTaggedUnion<T extends object, K extends keyof T> = {
-    [V in Tags<T, K>]: Extract<T, Record<K, V>>;
+    [P in PatternKey<Tags<T, K>>]: Extract<T, Record<K, PatternParam<P>>>;
 };
 
 type Handlers<T extends object, K extends keyof T, R> = {
-    [V in Tags<T, K>]: UnaryFn<MapTaggedUnion<T, K>[V], R>;
+    [P in PatternKey<Tags<T, K>>]: UnaryFn<MapTaggedUnion<T, K>[P], R>;
 };
 
-// The members `Handled` covers. Mapping over `Tags` keeps every index within
+// The members `Handled` covers. Mapping over the projected keys keeps every
-// `MapTaggedUnion`'s keys, and the conditional drops a stray key outside `T` so
+// index within `MapTaggedUnion`'s keys, and the conditional drops a stray key
-// it cannot widen the remainder. The remainder is `Exclude<T, …>`, mirroring
+// outside `T` so it cannot widen the remainder. The remainder is
-// the primitive-union matcher's `Exclude<T, PatternParam<keyof Handled>>`.
+// `Exclude<T, …>`, mirroring the primitive-union matcher's
+// `Exclude<T, PatternParam<keyof Handled>>`.
 type HandledMembers<T extends object, K extends keyof T, Handled> = {
-    [V in Tags<T, K>]: V extends keyof Handled
+    [P in PatternKey<Tags<T, K>>]: P extends keyof Handled
-        ? MapTaggedUnion<T, K>[V]
+        ? MapTaggedUnion<T, K>[P]
         : never;
-}[Tags<T, K>];
+}[PatternKey<Tags<T, K>>];
 
 // The fallback is a *second argument*, not a property of the handler map, so
 // its parameter can be the remainder the map left open. See development/library.md.
@@ -55,7 +62,7 @@ type Fallback<T extends object, K extends keyof T, Handled, R> = UnaryFn<
 // inference; see the primitive-union matcher for why a conditional in the fallback's
 // parameter is evaluated too early.
 type MustBePartial<T extends object, K extends keyof T, Handled> =
-    Tags<T, K> extends keyof Handled ? RedundantFallback : unknown;
+    PatternKey<Tags<T, K>> extends keyof Handled ? RedundantFallback : unknown;
 
 // TypeScript does not apply the excess-property check to a generic constraint,
 // so `Exact` restores it for the generic forms.
@@ -92,13 +99,26 @@ interface TaggedUnionMatcherWidening<T extends object, K extends keyof T> {
     ): UnaryFn<T, PatternReturns<Handled> | R>;
 }
 
+// The key-taking step of the curried factory. Naming it lets the factory return
+// `dispatch` directly, the tacit twin of the primitive-union factory's bare
+// `=> dispatch`.
+type TaggedUnionMatcherFactory<T extends object> = <K extends Discriminated<T>>(
+    k: K,
+) => TaggedUnionMatcherStrict<T, K>;
+
+type TaggedUnionMatcherWideningFactory<T extends object> = <
+    K extends Discriminated<T>,
+>(
+    k: K,
+) => TaggedUnionMatcherWidening<T, K>;
+
 const dispatch =
     (k: PropertyKey) =>
     (handlers: HandlerMap, fallback?: UnaryFn<never, unknown>) =>
     (shape: object): unknown => {
         // `object` carries no index signature, so the read needs the assertion;
-        // the factory admits only keys whose values are `string | number` tags,
+        // the factory admits only keys whose values are tags, and the map keys
-        // so the result is narrowed to the map's key space.
+        // them by `PatternKey`, so the result is narrowed to the map's key space.
         // oxlint-disable-next-line typescript/no-unsafe-type-assertion
         const tag = (shape as UnknownRecord)[k] as string | number;
         return (
@@ -113,12 +133,10 @@ const dispatch =
         );
     };
 
-export const getTaggedUnionMatcher =
+export const getTaggedUnionMatcher = <
-    <T extends object>() =>
+    T extends object,
-    <K extends Discriminated<T>>(k: K): TaggedUnionMatcherStrict<T, K> =>
+>(): TaggedUnionMatcherFactory<T> => dispatch;
-        dispatch(k);
 
-export const getTaggedUnionMatcherW =
+export const getTaggedUnionMatcherW = <
-    <T extends object>() =>
+    T extends object,
-    <K extends Discriminated<T>>(k: K): TaggedUnionMatcherWidening<T, K> =>
+>(): TaggedUnionMatcherWideningFactory<T> => dispatch;
-        dispatch(k);