bugfix-min-max-async

uriva · Nov 8, 2023 · 32220b3 · 32220b3
1 parent 033af8a
commit 32220b3
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Showing 2 changed files with 20 additions and 7 deletions.
diff --git a/src/reduce.test.ts b/src/reduce.test.ts
@@ -44,3 +44,6 @@ Deno.test("max call stack is not a limit on array size", () => {
   }
   assertEquals(max((x) => x)(bigArray), size - 1);
 });
+
+const _1: number = min((x: number) => x)([1, 2, 3, 4]);
+const _2: number = min((x: number) => x)([1, 2, 3, 4]);
diff --git a/src/reduce.ts b/src/reduce.ts
@@ -1,4 +1,4 @@
-import { Func, ReturnTypeUnwrapped } from "./typing.ts";
+import { AsyncFunction, Func, ReturnTypeUnwrapped } from "./typing.ts";
 
 const reduceHelper = <
   State,
@@ -33,14 +33,19 @@ export const reduce = <Function extends (state: any, element: any) => any>(
 
 export const min = <F extends Func>(key: F) => (xs: Parameters<F>[0][]) =>
   reduceHelper(
-    (s: Parameters<F>[0], x: Parameters<F>[0]) => {
+    (
+      s: Parameters<F>[0],
+      x: Parameters<F>[0],
+    ): F extends AsyncFunction ? Promise<Parameters<F>[0]>
+      : Parameters<F>[0] => {
       const keyS = key(s);
       const keyX = key(x);
-      return (keyS instanceof Promise || keyX instanceof Promise)
+      return ((keyS instanceof Promise || keyX instanceof Promise)
         ? Promise.all([keyS, keyX]).then(([keyS, keyX]) => keyS < keyX ? s : x)
         : key(s) < key(x)
         ? s
-        : x;
+        : x) as F extends AsyncFunction ? Promise<Parameters<F>[0]>
+          : Parameters<F>[0];
     },
     xs[0],
     xs,
@@ -49,14 +54,19 @@ export const min = <F extends Func>(key: F) => (xs: Parameters<F>[0][]) =>
 
 export const max = <F extends Func>(key: F) => (xs: Parameters<F>[0][]) =>
   reduceHelper(
-    (s: Parameters<F>[0], x: Parameters<F>[0]) => {
+    (
+      s: Parameters<F>[0],
+      x: Parameters<F>[0],
+    ): F extends AsyncFunction ? Promise<Parameters<F>[0]>
+      : Parameters<F>[0] => {
       const keyS = key(s);
       const keyX = key(x);
-      return (keyS instanceof Promise || keyX instanceof Promise)
+      return ((keyS instanceof Promise || keyX instanceof Promise)
         ? Promise.all([keyS, keyX]).then(([keyS, keyX]) => keyS < keyX ? x : s)
         : key(s) < key(x)
         ? x
-        : s;
+        : s) as F extends AsyncFunction ? Promise<Parameters<F>[0]>
+          : Parameters<F>[0];
     },
     xs[0],
     xs,