feat: support attaching effect without store param

Effector/Attach.swift

@@ -1,3 +1,25 @@
+
+public func attach<Params, MappedParams, Done, Fail>(
+    name: String? = nil,
+    effect fx: Effect<MappedParams, Done, Fail>,
+    map: @escaping (Params) -> MappedParams
+) -> Effect<Params, Done, Fail> {
+    let handler = fx.getCurrent()
+
+    let attached = Effect<Params, Done, Fail>(name: name ?? "attach", isDerived: true) { params in
+        try await handler(map(params))
+    }
+
+    return attached
+}
+
+public func attach<Params, Done, Fail>(
+    name: String? = nil,
+    effect fx: Effect<Params, Done, Fail>
+) -> Effect<Params, Done, Fail> {
+    return attach(effect: fx, map: { $0 })
+}
+
 public func attach<State, Params, Done, Fail>(
     name: String? = nil,
     store: Store<State>,

Tests/EffectorTests/AttachTests.swift

@@ -2,6 +2,31 @@
 import XCTest
 
 final class AttachTests: XCTestCase {
+    func testAttachCreatesEffect() async throws {
+        let fx = Effect<Void, Int, Error> { 1 }
+        let attached = attach(effect: fx)
+
+        var isOriginalFxCalled = false
+        fx.watch { _ in isOriginalFxCalled = true }
+
+        var isAttachedFxCalled = false
+        attached.watch { _ in isAttachedFxCalled = true }
+
+        await attached()
+
+        XCTAssertFalse(isOriginalFxCalled)
+        XCTAssertTrue(isAttachedFxCalled)
+    }
+
+    func testAttachWithMappedParams() async throws {
+        let fx = Effect<Int, Int, Error> { $0 }
+        let attached = attach(effect: fx, map: { $0 + 10 })
+
+        let got = try await attached(1).get()
+
+        XCTAssertEqual(got, 11)
+    }
+
     func testAttachEffect() async throws {
         let store = Store(10)
         let inc = Effect<Int, Int, Error> { $0 + 1 }