fix Config.nested mapping

Author: patroza

.changeset/bright-trees-count.md

@@ -0,0 +1,5 @@
+---
+"effect-app": patch
+---
+
+fix config nested

packages/effect-app/src/Config.ts

@@ -0,0 +1,14 @@
+import { type Config, make } from "effect/Config"
+import { dual } from "effect/Function"
+
+import * as ConfigProvider from "./ConfigProvider.js"
+
+export const nested: {
+  (name: string): <A>(self: Config<A>) => Config<A>
+  <A>(self: Config<A>, name: string): Config<A>
+} = dual(
+  2,
+  <A>(self: Config<A>, name: string): Config<A> => make((provider) => self.parse(ConfigProvider.nested(provider, name)))
+)
+
+export * from "effect/Config"

packages/effect-app/src/ConfigProvider.ts

@@ -0,0 +1,48 @@
+import { type ConfigProvider, make, type Path } from "effect/ConfigProvider"
+import { dual } from "effect/Function"
+
+/**
+ * Scopes a provider so that all lookups are prefixed with the given path
+ * segments.
+ *
+ * When to use:
+ * - Namespacing config under a prefix like `"app"` or `"database"`.
+ * - Reusing the same provider shape for multiple sub-configs.
+ *
+ * Accepts a single string or a full `Path` array. The prefix is prepended
+ * *after* any `mapInput` transformation runs, so ordering matters when
+ * composing with {@link mapInput} or {@link constantCase}.
+ *
+ * Supports both data-last and data-first calling conventions.
+ *
+ * **Example** (Nesting under a prefix)
+ *
+ * ```ts
+ * import { ConfigProvider } from "effect"
+ *
+ * const provider = ConfigProvider.fromEnv({
+ *   env: { APP_HOST: "localhost", APP_PORT: "3000" }
+ * })
+ *
+ * // Lookups for ["HOST"] now resolve to ["APP", "HOST"]
+ * const scoped = ConfigProvider.nested(provider, "APP")
+ * ```
+ *
+ * @see {@link mapInput} – for arbitrary path transformations
+ *
+ * @category Combinators
+ * @since 4.0.0
+ */
+export const nested: {
+  (prefix: string | Path): (self: ConfigProvider) => ConfigProvider
+  (self: ConfigProvider, prefix: string | Path): ConfigProvider
+} = dual(
+  2,
+  (self: ConfigProvider, prefix: string | Path): ConfigProvider => {
+    let path: Path = typeof prefix === "string" ? [prefix] : prefix
+    if (self.mapInput) path = self.mapInput(path)
+    return make(self.get, self.mapInput, self.prefix ? [...self.prefix, ...path] : path)
+  }
+)
+
+export * from "effect/ConfigProvider"

packages/effect-app/src/client/apiClientFactory.ts

@@ -1,12 +1,12 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import * as Config from "effect/Config"
 import { flow } from "effect/Function"
 import * as Layer from "effect/Layer"
 import * as ManagedRuntime from "effect/ManagedRuntime"
 import * as Predicate from "effect/Predicate"
 import * as Schema from "effect/Schema"
 import * as Struct from "effect/Struct"
 import { Rpc, RpcClient, RpcGroup, RpcSerialization } from "effect/unstable/rpc"
+import * as Config from "../Config.js"
 import * as Effect from "../Effect.js"
 import { HttpClient, HttpClientRequest } from "../http.js"
 import * as Option from "../Option.js"

packages/effect-app/src/index.ts

@@ -6,6 +6,8 @@ export * as Fnc from "./Function.js"
 export * as Utils from "./utils.js"
 
 export * as Array from "./Array.js"
+export * as Config from "./Config.js"
+export * as ConfigProvider from "./ConfigProvider.js"
 export * as Effect from "./Effect.js"
 export * as Layer from "./Layer.js"
 export * as NonEmptySet from "./NonEmptySet.js"