From 734e6a6de7fd56b838e00a82490c6a82965e0125 Mon Sep 17 00:00:00 2001
From: Jason Kuhrt <jasonkuhrt@me.com>
Date: Mon, 5 Sep 2022 15:49:23 -0400
Subject: [PATCH] fix(match): else handler gets records minus those
 data-matched

Previously the `.else` handler in this case would statically receive
`A|B|C`. Now it correctly only receives `B|C`.

```ts
Alge.match(dataABC)
  .A(...)
  .else((data) => ...)
```
---
 src/match.ts              | 8 ++++++--
 tests/match/match.spec.ts | 6 +++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/match.ts b/src/match.ts
index d458d97..4e6eb52 100644
--- a/src/match.ts
+++ b/src/match.ts
@@ -13,7 +13,7 @@ Terminology:
  */
 
 import { OmitTag } from './core/types.js'
-import { inspect } from './lib/utils.js'
+import { inspect, ObjectValues } from './lib/utils.js'
 import { SomeRecord } from './record/types/controller.js'
 import isMatch from 'lodash.ismatch'
 
@@ -151,6 +151,10 @@ type PostMatcher<ADT extends SomeRecord, PreviousTagsMatched extends string, Res
   ADT['_tag'] extends PreviousTagsMatched ? {
     done: () => Result
   } : {
-    else: <ThisResult extends unknown>(value: ThisResult| ((data: ADT) => ThisResult)) => Result|ThisResult
+    else: <ThisResult extends unknown>(value: ThisResult | ((data: ExcludeByTag<ADT, PreviousTagsMatched>) => ThisResult)) => Result | ThisResult
   }
 )
+
+type ExcludeByTag<Record extends SomeRecord, Tag extends string> = Record extends { _tag: Tag }
+  ? never
+  : Record
diff --git a/tests/match/match.spec.ts b/tests/match/match.spec.ts
index 1370a46..ee866f5 100644
--- a/tests/match/match.spec.ts
+++ b/tests/match/match.spec.ts
@@ -102,6 +102,10 @@ describe(`.<tag> (Data Matcher)`, () => {
 })
 
 describe(`.else`, () => {
+  it('does not receive tag X when a data matcher for X has been set', () => {
+    const builder = Alge.match(a as ab).A(() => 1)
+    builder.else((data) => expectType<B>(data))
+  })
   it(`not available if no matchers have been defined`, () => {
     const builder = Alge.match(ab)
     // @ts-expect-error Not available yet.
@@ -119,7 +123,7 @@ describe(`.else`, () => {
   it(`is available if some but not all tag matchers have been defined`, () => {
     const builder = Alge.match(ab).A(() => 1 as const)
     expectType<typeof builder.else>(
-      0 as any as <ThisResult>(value: ThisResult | ((data: ab) => ThisResult)) => 1 | ThisResult
+      0 as any as <ThisResult>(value: ThisResult | ((data: B) => ThisResult)) => 1 | ThisResult
     )
     expect(builder.else).toBeDefined()
   })