Typeguard tweak.

jordanburke · Dec 20, 2024 · f15e7de · f15e7de
1 parent bda6191
commit f15e7de
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Showing 3 changed files with 3 additions and 3 deletions.
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "functype",
-  "version": "0.8.39",
+  "version": "0.8.40",
   "description": "A smallish functional library for TypeScript",
   "author": "[email protected]",
   "license": "MIT",

diff --git a/src/list/List.ts b/src/list/List.ts
@@ -6,7 +6,7 @@ import { None, Option } from "../option/Option"
 import { Set } from "../set/Set"
 import { Typeable } from "../typeable/Typeable"
 
-type TypeGuard<A, B extends A> = (a: A) => a is B
+type TypeGuard<A, B extends A> = (a: A | undefined) => a is B
 
 type FilterFn<A> = {
   <B extends A>(p: TypeGuard<A, B>): List<B>

diff --git a/test/list/list.spec.ts b/test/list/list.spec.ts
@@ -181,7 +181,7 @@ describe("List", () => {
     })
 
     it("filter with regular predicate", () => {
-      const largeShapes = shapes.filter((shape) => shape.value > 4)
+      const largeShapes = shapes.filter((shape) => !!shape && shape.value > 4)
       expect(largeShapes.toValue()).toEqual({
         _tag: "List",
         value: [{ _tag: "circle", kind: "circle", value: 5 }],