fix-assert-typing

src/debug.test.ts

@@ -8,6 +8,7 @@ import { assert, timeit, tryCatch } from "./debug.ts";
 import { assertEquals, assertThrows } from "std-assert";
 import { sleep } from "./time.ts";
 import { throwerCatcherWithValue } from "./index.ts";
+import { pipe } from "./composition.ts";
 
 Deno.test("timeit", () => {
   const logger = (x: string) => console.log(x);
@@ -53,6 +54,11 @@ Deno.test("assert", () => {
   assert(condition, err)(10);
 });
 
+const _assertTyping: number = pipe(
+  (x: number) => x,
+  assert((x: number) => x > 3, "bla"),
+)(7);
+
 Deno.test("assert async", async () => {
   const err = "not greater than 7";
   const condition = (x: number) => Promise.resolve(x > 7);

src/debug.ts

@@ -2,12 +2,14 @@ import type {
   AsyncFunction,
   Func,
   IsAsync,
+  ParamOf,
   ReturnTypeUnwrapped,
 } from "./typing.ts";
-import { pipe } from "./composition.ts";
+import { pipe, sideEffect } from "./composition.ts";
 import { pairRight } from "./juxt.ts";
 import { isPromise } from "./promise.ts";
 import { currentLocation } from "./trace.ts";
+import { letIn } from "./operator.ts";
 
 export const sideLog = <T>(x: T) => {
   console.log(currentLocation(3), x);
@@ -84,13 +86,16 @@ export const timeit = <F extends Func>(
     return result;
   }) as F;
 
-export const assert = <T>(
-  condition: (_: T) => boolean | Promise<boolean>,
+export const assert = <F extends Func>(
+  condition: F,
   errorMessage: string,
-) =>
+): true extends IsAsync<F> ? ((t: ParamOf<F>) => Promise<ParamOf<F>>)
+  : ((t: ParamOf<F>) => ParamOf<F>) =>
+  // @ts-expect-error not sure
   pipe(
+    // @ts-expect-error not sure
     pairRight(condition),
-    ([value, passed]) => {
+    ([value, passed]: [ParamOf<F>, boolean]) => {
       if (!passed) throw new Error(errorMessage);
       return value;
     },