Make it easy to convert a DateTime.Zoned to a DateTime.Utc (#4375)

Author: thewilkybarkid

.changeset/sixty-mice-occur.md

@@ -0,0 +1,5 @@
+---
+"effect": minor
+---
+
+Make it easy to convert a DateTime.Zoned to a DateTime.Utc

packages/effect/src/DateTime.ts

@@ -437,6 +437,23 @@ export const unsafeNow: LazyArg<Utc> = Internal.unsafeNow
 // time zones
 // =============================================================================
 
+/**
+ * For a `DateTime` returns a new `DateTime.Utc`.
+ *
+ * @since 3.13.0
+ * @category time zones
+ * @example
+ * ```ts
+ * import { DateTime } from "effect"
+ *
+ * const now = DateTime.unsafeMakeZoned({ year: 2024 }, { timeZone: "Europe/London" })
+ *
+ * // set as UTC
+ * const utc: DateTime.Utc = DateTime.toUtc(now)
+ * ```
+ */
+export const toUtc: (self: DateTime) => Utc = Internal.toUtc
+
 /**
  * Set the time zone of a `DateTime`, returning a new `DateTime.Zoned`.
  *

packages/effect/src/internal/dateTime.ts

@@ -306,6 +306,9 @@ export const unsafeNow: LazyArg<DateTime.Utc> = () => makeUtc(Date.now())
 // time zones
 // =============================================================================
 
+/** @internal */
+export const toUtc = (self: DateTime.DateTime): DateTime.Utc => makeUtc(self.epochMillis)
+
 /** @internal */
 export const setZone: {
   (zone: DateTime.TimeZone, options?: {

packages/effect/test/DateTime.test.ts

@@ -421,4 +421,21 @@ describe("DateTime", () => {
     const dt = DateTime.unsafeMakeZoned(date)
     deepStrictEqual(dt.zone, DateTime.zoneMakeOffset(60 * 60 * 1000))
   })
+
+  describe("toUtc", () => {
+    it.effect("with a Utc", () =>
+      Effect.gen(function*() {
+        const dt = DateTime.unsafeMake("2024-01-01T01:00:00")
+        strictEqual(dt.toJSON(), "2024-01-01T01:00:00.000Z")
+      }))
+
+    it.effect("with a Zoned", () =>
+      Effect.gen(function*() {
+        const dt = DateTime.unsafeMakeZoned("2024-01-01T01:00:00Z", {
+          timeZone: "Pacific/Auckland",
+          adjustForTimeZone: true
+        })
+        strictEqual(dt.toJSON(), "2023-12-31T12:00:00.000Z")
+      }))
+  })
 })

packages/platform-node/test/HttpApi.test.ts

@@ -445,7 +445,7 @@ const HttpUsersLive = HttpApiBuilder.group(
               new User({
                 id: 1,
                 name: `page ${_.headers.page}`,
-                createdAt: DateTime.unsafeMake(now.epochMillis)
+                createdAt: DateTime.toUtc(now)
               })
             ]))
         .handle("upload", (_) =>