From 5c1fdbad431efcd96154415d0aa4e68b43854344 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julien=20Valverd=C3=A9?= <julien.valverde@mailo.com>
Date: Tue, 26 May 2026 04:18:59 +0200
Subject: [PATCH] Refactor

---
 packages/effect-lens/src/Lens.ts | 395 ++++++++++++++-----------------
 1 file changed, 174 insertions(+), 221 deletions(-)

diff --git a/packages/effect-lens/src/Lens.ts b/packages/effect-lens/src/Lens.ts
index ecb2adf..f467d71 100644
--- a/packages/effect-lens/src/Lens.ts
+++ b/packages/effect-lens/src/Lens.ts
@@ -1,4 +1,4 @@
-import { Array, Chunk, type Context, Effect, Function, identity, type ManagedRuntime, Option, Pipeable, Predicate, PubSub, Readable, Ref, type Runtime, Stream, type SubscriptionRef, type SynchronizedRef } from "effect"
+import { Array, Chunk, type Context, Effect, Function, identity, Option, Pipeable, Predicate, PubSub, Readable, Ref, Stream, type SubscriptionRef, type SynchronizedRef } from "effect"
 import type { NoSuchElementException } from "effect/Cause"
 import * as Subscribable from "./Subscribable.js"
 
@@ -28,60 +28,24 @@ extends Subscribable.Subscribable<A, ER, RR> {
 export const isLens = (u: unknown): u is Lens<unknown, unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, LensTypeId)
 
 
-export const LensStepTypeId: unique symbol = Symbol.for("@effect-fc/Lens/LensStep")
-export type LensStepTypeId = typeof LensStepTypeId
-
-export interface LensFrame<in out A, in out EW = never, in out RW = never> {
-    readonly value: A
-    readonly commit: <E = never, R = never>(
-        next: Effect.Effect<A, E, R>
-    ) => Effect.Effect<void, EW | E, RW | R>
-}
-
-export interface LensStep<
-    in out A,
-    in out B,
-    in out ER = never,
-    in out ESR = never,
-    in out EW = never,
-    in out ESW = never,
-    in out RR = never,
-    in out RSR = never,
-    in out RW = never,
-    in out RSW = never,
-> {
-    readonly [LensStepTypeId]: LensStepTypeId
-    readonly access: (effect: Effect.Effect<LensFrame<B, ESW, RSW>, ESR, RSR>) => Effect.Effect<LensFrame<A, EW, RW>, ER, RR>
-    readonly transformStream: (stream: Stream.Stream<B, ESR, RSR>) => Stream.Stream<A, ER, RR>
-}
-
-export const isLensStep = (u: unknown): u is LensStep<unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, LensStepTypeId)
-
-
 export const LensImplTypeId: unique symbol = Symbol.for("@effect-fc/Lens/LensImpl")
 export type LensImplTypeId = typeof LensImplTypeId
 
-export const isLensImpl = (u: unknown): u is LensImpl<unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, LensImplTypeId)
-
-export const asLensImpl = <A, ER, EW, RR, RW>(
-    lens: Lens<A, ER, EW, RR, RW>
-): LensImpl<A, unknown, ER, unknown, EW, unknown, RR, unknown, RW, unknown> => {
-    if (!isLensImpl(lens))
-        throw new Error("Not a 'LensImpl'.")
-    return lens as LensImpl<A, unknown, ER, unknown, EW, unknown, RR, unknown, RW, unknown>
+export declare namespace LensImpl {
+    export interface Frame<in out A, in out EW = never, in out RW = never> {
+        readonly value: A
+        readonly commit: <E = never, R = never>(
+            next: Effect.Effect<A, E, R>
+        ) => Effect.Effect<void, EW | E, RW | R>
+    }
 }
 
 export abstract class LensImpl<
     in out A,
-    in out B,
     in out ER = never,
-    in out ESR = never,
     in out EW = never,
-    in out ESW = never,
     in out RR = never,
-    in out RSR = never,
     in out RW = never,
-    in out RSW = never,
 >
 extends Pipeable.Class() implements Lens<A, ER, EW, RR, RW> {
     readonly [Readable.TypeId]: Readable.TypeId = Readable.TypeId
@@ -89,39 +53,14 @@ extends Pipeable.Class() implements Lens<A, ER, EW, RR, RW> {
     readonly [LensTypeId]: LensTypeId = LensTypeId
     readonly [LensImplTypeId]: LensImplTypeId = LensImplTypeId
 
-    readonly steps: readonly LensStep<unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown>[] = []
-
-    abstract readonly sourceGet: Effect.Effect<B, ESR, RSR>
-    abstract readonly sourceChanges: Stream.Stream<B, ESR, RSR>
-    abstract sourceCommit(b: B): Effect.Effect<void, ESW, RSW>
+    abstract readonly access: Effect.Effect<LensImpl.Frame<A, EW, RW>, ER, RR>
+    abstract readonly changes: Stream.Stream<A, ER, RR>
     abstract readonly withLock: <A1, E1, R1>(self: Effect.Effect<A1, E1, R1>) => Effect.Effect<A1, EW | E1, RW | R1>
 
-    get access(): Effect.Effect<LensFrame<A, EW, RW>, ER, RR> {
-        let effect: Effect.Effect<LensFrame<unknown, unknown, unknown>, unknown, unknown> = Effect.map(
-            this.sourceGet,
-            value => ({
-                value,
-                commit: next => Effect.flatMap(next, value => this.sourceCommit(value as B)),
-            }),
-        )
-
-        for (const step of this.steps)
-            effect = step.access(effect) as Effect.Effect<LensFrame<unknown, unknown, unknown>, unknown, unknown>
-
-        return effect as Effect.Effect<LensFrame<A, EW, RW>, ER, RR>
-    }
-
     get get(): Effect.Effect<A, ER, RR> {
         return Effect.map(this.access, frame => frame.value)
     }
 
-    get changes(): Stream.Stream<A, ER, RR> {
-        let stream: Stream.Stream<unknown, unknown, unknown> = this.sourceChanges
-        for (const step of this.steps)
-            stream = step.transformStream(stream)
-        return stream as Stream.Stream<A, ER, RR>
-    }
-
     modifyEffect<C, E1 = never, R1 = never>(
         f: (a: A) => Effect.Effect<readonly [C, A], E1, R1>,
     ): Effect.Effect<C, ER | EW | E1, RR | RW | R1> {
@@ -135,77 +74,128 @@ extends Pipeable.Class() implements Lens<A, ER, EW, RR, RW> {
     }
 }
 
+export const isLensImpl = (u: unknown): u is LensImpl<unknown, unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, LensImplTypeId)
+
+export const asLensImpl = <A, ER, EW, RR, RW>(
+    lens: Lens<A, ER, EW, RR, RW>
+): LensImpl<A, ER, EW, RR, RW> => {
+    if (!isLensImpl(lens))
+        throw new Error("Not a 'LensImpl'.")
+    return lens as LensImpl<A, ER, EW, RR, RW>
+}
+
 
 export declare namespace LensLazyImpl {
     export interface Source<in out B, in out ESW = never, in out ESR = never, in out RSR = never, in out RSW = never> {
-        readonly sourceGet: Effect.Effect<B, ESR, RSR>
-        readonly sourceChanges: Stream.Stream<B, ESR, RSR>
-        readonly sourceCommit: (b: B) => Effect.Effect<void, ESW, RSW>
+        readonly get: Effect.Effect<B, ESR, RSR>
+        readonly changes: Stream.Stream<B, ESR, RSR>
+        readonly commit: (b: B) => Effect.Effect<void, ESW, RSW>
         readonly withLock: <A1, E1, R1>(self: Effect.Effect<A1, E1, R1>) => Effect.Effect<A1, E1, R1>
     }
 }
 
 export class LensLazyImpl<
-    in out A,
     in out B,
-    in out ER = never,
-    in out ESR = never,
-    in out EW = never,
     in out ESW = never,
-    in out RR = never,
+    in out ESR = never,
     in out RSR = never,
-    in out RW = never,
     in out RSW = never,
 >
-extends LensImpl<A, B, ER, ESR, EW, ESW, RR, RSR, RW, RSW> {
+extends LensImpl<B, ESR, ESW, RSR, RSW> {
     constructor(
         readonly source: LensLazyImpl.Source<B, ESW, ESR, RSR, RSW>,
     ) {
         super()
     }
 
-    get sourceGet() { return this.source.sourceGet }
-    get sourceChanges() { return this.source.sourceChanges }
-    sourceCommit(b: B) { return this.source.sourceCommit(b) }
+    get access(): Effect.Effect<LensImpl.Frame<B, ESW, RSW>, ESR, RSR> {
+        return Effect.map(
+            this.source.get,
+            value => ({
+                value,
+                commit: next => Effect.flatMap(next, value => this.source.commit(value)),
+            }),
+        )
+    }
+
+    get changes() { return this.source.changes }
     get withLock() { return this.source.withLock }
 }
 
 /**
  * Creates a `Lens` by supplying how to read the current value, observe changes, and apply transformations.
  */
-export const makeLazy = <B, ESW, ESR, RSR, RSW>(
+export const make = <B, ESW, ESR, RSR, RSW>(
     source: LensLazyImpl.Source<B, ESW, ESR, RSR, RSW>
 ): Lens<B, ESR, ESW, RSR, RSW> => new LensLazyImpl(source)
 
+
+export declare namespace DerivedLensImpl {
+    export interface Source<
+        in out A,
+        in out B,
+        in out ER = never,
+        in out ESR = never,
+        in out EW = never,
+        in out ESW = never,
+        in out RR = never,
+        in out RSR = never,
+        in out RW = never,
+        in out RSW = never,
+    > {
+        readonly access: (effect: Effect.Effect<LensImpl.Frame<B, ESW, RSW>, ESR, RSR>) => Effect.Effect<LensImpl.Frame<A, EW, RW>, ER, RR>
+        readonly transformStream: (stream: Stream.Stream<B, ESR, RSR>) => Stream.Stream<A, ER, RR>
+    }
+}
+
+export class DerivedLensImpl<
+    in out A,
+    in out B,
+    in out ER = never,
+    in out PER = never,
+    in out EW = never,
+    in out PEW = never,
+    in out RR = never,
+    in out PRR = never,
+    in out RW = never,
+    in out PRW = never,
+>
+extends LensImpl<A, ER, EW, RR, RW> {
+    constructor(
+        readonly parent: LensImpl<B, PER, PEW, PRR, PRW>,
+        readonly source: DerivedLensImpl.Source<A, B, ER, PER, EW, PEW, RR, PRR, RW, PRW>,
+    ) {
+        super()
+    }
+
+    get access(): Effect.Effect<LensImpl.Frame<A, EW, RW>, ER, RR> {
+        return this.source.access(this.parent.access)
+    }
+
+    get changes(): Stream.Stream<A, ER, RR> {
+        return this.source.transformStream(this.parent.changes)
+    }
+
+    get withLock() {
+        return this.parent.withLock
+    }
+}
+
 /**
- * Derives a new `Lens` by immutably appending a step to an existing `LensImpl`.
+ * Derives a new `Lens` by linking a step to an existing parent lens.
  */
 export const derive: {
-    <A, B, ER, ESR, EW, ESW, RR, RSR, RW, RSW, C, ER2, EW2, RR2, RW2>(
-        self: LensImpl<A, B, ER, ESR, EW, ESW, RR, RSR, RW, RSW>,
-        step: LensStep<C, A, ER2, ER, EW2, EW, RR2, RR, RW2, RW>,
+    <A, ER, EW, RR, RW, C, ER2, EW2, RR2, RW2>(
+        self: Lens<A, ER, EW, RR, RW>,
+        source: DerivedLensImpl.Source<C, A, ER2, ER, EW2, EW, RR2, RR, RW2, RW>,
     ): Lens<C, ER2, EW2, RR2, RW2>
     <A, ER, EW, RR, RW, C, ER2, EW2, RR2, RW2>(
-        step: LensStep<C, A, ER2, ER, EW2, EW, RR2, RR, RW2, RW>,
-    ): <B, ESR, ESW, RSR, RSW>(
-        self: LensImpl<A, B, ER, ESR, EW, ESW, RR, RSR, RW, RSW>
-    ) => Lens<C, ER2, EW2, RR2, RW2>
-} = Function.dual(2, <A, B, ER, ESR, EW, ESW, RR, RSR, RW, RSW, C, ER2, EW2, RR2, RW2>(
-    self: LensImpl<A, B, ER, ESR, EW, ESW, RR, RSR, RW, RSW>,
-    step: LensStep<C, A, ER2, ER, EW2, EW, RR2, RR, RW2, RW>,
-): Lens<C, ER2, EW2, RR2, RW2> => Object.defineProperty(
-    Object.defineProperties(
-        Object.create(Object.getPrototypeOf(self)),
-        Object.getOwnPropertyDescriptors(self),
-    ),
-    "steps",
-    {
-        configurable: true,
-        enumerable: true,
-        value: [...self.steps, step as LensStep<unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown, unknown>],
-        writable: false,
-    },
-) as Lens<C, ER2, EW2, RR2, RW2>)
+        source: DerivedLensImpl.Source<C, A, ER2, ER, EW2, EW, RR2, RR, RW2, RW>,
+    ): (self: Lens<A, ER, EW, RR, RW>) => Lens<C, ER2, EW2, RR2, RW2>
+} = Function.dual(2, <A, ER, EW, RR, RW, C, ER2, EW2, RR2, RW2>(
+    self: Lens<A, ER, EW, RR, RW>,
+    source: DerivedLensImpl.Source<C, A, ER2, ER, EW2, EW, RR2, RR, RW2, RW>,
+): Lens<C, ER2, EW2, RR2, RW2> => new DerivedLensImpl(asLensImpl(self), source))
 
 
 export declare namespace SynchronizedRefLensImpl {
@@ -217,7 +207,7 @@ export declare namespace SynchronizedRefLensImpl {
 }
 
 export class SynchronizedRefLensImpl<in out A>
-extends LensImpl<A, A, never, never, never, never, never, never, never, never> {
+extends LensImpl<A, never, never, never, never> {
     readonly ref: SynchronizedRefLensImpl.SynchronizedRefWithInternals<A>
 
     constructor(
@@ -227,9 +217,17 @@ extends LensImpl<A, A, never, never, never, never, never, never, never, never> {
         this.ref = ref as SynchronizedRefLensImpl.SynchronizedRefWithInternals<A>
     }
 
-    get sourceGet() { return this.ref.get }
-    get sourceChanges() { return Stream.unwrap(Effect.map(this.ref.get, Stream.make)) }
-    sourceCommit(a: A) { return Ref.set(this.ref.ref, a) }
+    get access(): Effect.Effect<LensImpl.Frame<A>, never, never> {
+        return Effect.map(
+            this.ref.get,
+            value => ({
+                value,
+                commit: next => Effect.flatMap(next, value => Ref.set(this.ref.ref, value)),
+            }),
+        )
+    }
+
+    get changes() { return Stream.unwrap(Effect.map(this.ref.get, Stream.make)) }
     get withLock() { return this.ref.withLock }
 }
 
@@ -254,7 +252,7 @@ export declare namespace SubscriptionRefLensImpl {
 }
 
 export class SubscriptionRefLensImpl<in out A>
-extends LensImpl<A, A, never, never, never, never, never, never, never, never> {
+extends LensImpl<A, never, never, never, never> {
     readonly ref: SubscriptionRefLensImpl.SubscriptionRefWithInternals<A>
 
     constructor(
@@ -264,9 +262,18 @@ extends LensImpl<A, A, never, never, never, never, never, never, never, never> {
         this.ref = ref as SubscriptionRefLensImpl.SubscriptionRefWithInternals<A>
     }
 
-    get sourceGet() { return this.ref.get }
-    get sourceChanges() { return this.ref.changes }
-    sourceCommit(a: A) {
+    get access(): Effect.Effect<LensImpl.Frame<A>, never, never> {
+        return Effect.map(
+            this.ref.get,
+            value => ({
+                value,
+                commit: next => Effect.flatMap(next, value => this.commit(value)),
+            }),
+        )
+    }
+
+    get changes() { return this.ref.changes }
+    commit(a: A) {
         return Effect.zipLeft(
             Ref.set(this.ref.ref, a),
             PubSub.publish(this.ref.pubsub, a),
@@ -288,10 +295,10 @@ export const fromSubscriptionRef = <A>(
  */
 export const unwrap = <A, ER, EW, RR, RW, E1, R1>(
     effect: Effect.Effect<Lens<A, ER, EW, RR, RW>, E1, R1>
-): Lens<A, ER | E1, ER | EW | E1, RR | R1, RR | RW | R1> => makeLazy<A, ER | EW | E1, ER | E1, RR | R1, RR | RW | R1>({
-    sourceGet: Effect.flatMap(effect, l => l.get),
-    sourceChanges: Stream.unwrap(Effect.map(effect, l => l.changes)),
-    sourceCommit: a => Effect.flatMap(
+): Lens<A, ER | E1, ER | EW | E1, RR | R1, RR | RW | R1> => make({
+    get: Effect.flatMap(effect, l => l.get),
+    changes: Stream.unwrap(Effect.map(effect, l => l.changes)),
+    commit: a => Effect.flatMap(
         effect,
         l => Effect.flatMap(asLensImpl(l).access, frame => frame.commit(Effect.succeed(a))),
     ),
@@ -338,25 +345,19 @@ export const mapEffect: {
     self: Lens<A, ER, EW, RR, RW>,
     get: (a: NoInfer<A>) => Effect.Effect<B, EGet, RGet>,
     set: (a: NoInfer<A>, b: B) => Effect.Effect<NoInfer<A>, ESet, RSet>,
-): Lens<B, ER | EGet, EW | ESet, RR | RGet, RW | RSet> => {
-    return derive(
-        asLensImpl(self),
-        {
-            [LensStepTypeId]: LensStepTypeId,
-            access: parent => Effect.flatMap(
-                parent,
-                frame => Effect.map(
-                    get(frame.value),
-                    value => ({
-                        value,
-                        commit: next => frame.commit(Effect.flatMap(next, b => set(frame.value, b))),
-                    }),
-                ),
-            ),
-            transformStream: stream => Stream.mapEffect(stream, get),
-        },
-    )
-})
+): Lens<B, ER | EGet, EW | ESet, RR | RGet, RW | RSet> => derive(self, {
+    access: parent => Effect.flatMap(
+        parent,
+        frame => Effect.map(
+            get(frame.value),
+            value => ({
+                value,
+                commit: next => frame.commit(Effect.flatMap(next, b => set(frame.value, b))),
+            }),
+        ),
+    ),
+    transformStream: Stream.mapEffect(get),
+}))
 
 /**
  * Derives a new `Lens` by applying synchronous getters and setters over the value inside an `Option`.
@@ -438,11 +439,10 @@ export const mapStream: {
 } = Function.dual(2, <A, ER, EW, RR, RW>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (changes: Stream.Stream<NoInfer<A>, NoInfer<ER>, NoInfer<RR>>) => Stream.Stream<NoInfer<A>, NoInfer<ER>, NoInfer<RR>>,
-): Lens<A, ER, EW, RR, RW> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
-    access: parent => parent,
+): Lens<A, ER, EW, RR, RW> => derive(self, {
+    access: identity,
     transformStream: f,
-} as LensStep<A, A, ER, ER, EW, EW, RR, RR, RW, RW>))
+}))
 
 
 /**
@@ -461,11 +461,10 @@ export const mapErrorRead: {
 } = Function.dual(2, <A, ER, EW, RR, RW, E2>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (error: NoInfer<ER>) => E2,
-): Lens<A, E2, EW, RR, RW> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
-    access: parent => Effect.mapError(parent, f),
-    transformStream: stream => Stream.mapError(stream, f),
-} as LensStep<A, A, E2, ER, EW, EW, RR, RR, RW, RW>))
+): Lens<A, E2, EW, RR, RW> => derive(self, {
+    access: Effect.mapError(f),
+    transformStream: Stream.mapError(f),
+}))
 
 /**
  * Transforms modify errors of a `Lens`.
@@ -484,14 +483,13 @@ export const mapErrorWrite: {
 } = Function.dual(2, <A, ER, EW, RR, RW, E2>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (error: unknown) => E2,
-): Lens<A, ER, E2, RR, RW> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
+): Lens<A, ER, E2, RR, RW> => derive(self, {
     access: parent => Effect.map(parent, frame => ({
         value: frame.value,
         commit: next => Effect.mapError(frame.commit(next), f),
     })),
-    transformStream: stream => stream,
-} as LensStep<A, A, ER, ER, E2, EW, RR, RR, RW, RW>))
+    transformStream: identity,
+}))
 
 /**
  * Transforms all errors of a `Lens`.
@@ -510,8 +508,7 @@ export const mapError: {
 } = Function.dual(2, <A, ER, EW, RR, RW, E2>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (error: unknown) => E2,
-): Lens<A, E2, E2, RR, RW> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
+): Lens<A, E2, E2, RR, RW> => derive(self, {
     access: parent => Effect.map(
         Effect.mapError(parent, f),
         frame => ({
@@ -519,8 +516,8 @@ export const mapError: {
             commit: next => Effect.mapError(frame.commit(next), f),
         }),
     ),
-    transformStream: stream => Stream.mapError(stream, f),
-} as LensStep<A, A, E2, ER, E2, EW, RR, RR, RW, RW>))
+    transformStream: Stream.mapError(f),
+}))
 
 /**
  * Recovers from read failures of a `Lens`.
@@ -538,11 +535,10 @@ export const catchAllRead: {
 } = Function.dual(2, <A, ER, EW, RR, RW, E2, R2>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (error: NoInfer<ER>) => Subscribable.Subscribable<A, E2, R2>,
-): Lens<A, E2, EW, RR | R2, RW> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
-    access: parent => Effect.catchAll(parent, error => asLensImpl(f(error) as Lens<A, E2, EW, R2, RW>).access),
-    transformStream: stream => Stream.catchAll(stream, error => f(error).changes),
-} as LensStep<A, A, E2, ER, EW, EW, RR | R2, RR, RW, RW>))
+): Lens<A, E2, EW, RR | R2, RW> => derive(self, {
+    access: Effect.catchAll(error => asLensImpl(f(error) as Lens<A, E2, EW, R2, RW>).access),
+    transformStream: Stream.catchAll(error => f(error).changes),
+}))
 
 /**
  * Runs an effect when read failures occur.
@@ -560,11 +556,10 @@ export const tapErrorRead: {
 } = Function.dual(2, <A, ER, EW, RR, RW, E2, R2>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (error: NoInfer<ER>) => Effect.Effect<any, E2, R2>,
-): Lens<A, ER | E2, EW, RR | R2, RW> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
-    access: parent => Effect.tapError(parent, f),
-    transformStream: stream => Stream.tapError(stream, f),
-} as LensStep<A, A, ER | E2, ER, EW, EW, RR | R2, RR, RW, RW>))
+): Lens<A, ER | E2, EW, RR | R2, RW> => derive(self, {
+    access: Effect.tapError(f),
+    transformStream: Stream.tapError(f),
+}))
 
 /**
  * Runs an effect when modify failures occur.
@@ -583,14 +578,13 @@ export const tapErrorWrite: {
 } = Function.dual(2, <A, ER, EW, RR, RW, E2, R2>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (error: unknown) => Effect.Effect<any, E2, R2>,
-): Lens<A, ER, EW | E2, RR, RW | R2> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
+): Lens<A, ER, EW | E2, RR, RW | R2> => derive(self, {
     access: parent => Effect.map(parent, frame => ({
         value: frame.value,
         commit: next => Effect.tapError(frame.commit(next), f),
     })),
-    transformStream: stream => stream,
-} as LensStep<A, A, ER, ER, EW | E2, EW, RR, RR, RW | R2, RW>))
+    transformStream: identity,
+}))
 
 /**
  * Runs an effect when any `Lens` failure occurs.
@@ -609,8 +603,7 @@ export const tapError: {
 } = Function.dual(2, <A, ER, EW, RR, RW, E2, R2>(
     self: Lens<A, ER, EW, RR, RW>,
     f: (error: unknown) => Effect.Effect<any, E2, R2>,
-): Lens<A, ER | E2, EW | E2, RR | R2, RW | R2> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
+): Lens<A, ER | E2, EW | E2, RR | R2, RW | R2> => derive(self, {
     access: parent => Effect.map(
         Effect.tapError(parent, f),
         frame => ({
@@ -618,8 +611,8 @@ export const tapError: {
             commit: next => Effect.tapError(frame.commit(next), f),
         }),
     ),
-    transformStream: stream => Stream.tapError(stream, f),
-} as LensStep<A, A, ER | E2, ER, EW | E2, EW, RR | R2, RR, RW | R2, RW>))
+    transformStream: Stream.tapError(f),
+}))
 
 
 /**
@@ -636,8 +629,7 @@ export const provideContext: {
 } = Function.dual(2, <A, ER, EW, RR, RW, R2>(
     self: Lens<A, ER, EW, RR, RW>,
     context: Context.Context<R2>,
-): Lens<A, ER, EW, Exclude<RR, R2>, Exclude<RW, R2>> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
+): Lens<A, ER, EW, Exclude<RR, R2>, Exclude<RW, R2>> => derive(self, {
     access: parent => Effect.map(
         Effect.provide(parent, context),
         frame => ({
@@ -645,46 +637,8 @@ export const provideContext: {
             commit: next => Effect.provide(frame.commit(Effect.provide(next, context)), context),
         }),
     ),
-    transformStream: stream => Stream.provideSomeContext(stream, context),
-} as LensStep<A, A, ER, ER, EW, EW, Exclude<RR, R2>, RR, Exclude<RW, R2>, RW>))
-
-/**
- * Provides a `Runtime` or `ManagedRuntime` to a `Lens`, removing it from both the read and write environments.
- *
- * `ManagedRuntime` may add its construction errors to both the read and write error channels.
- */
-export const provideRuntime: {
-    <R2>(
-        runtime: Runtime.Runtime<R2>,
-    ): <A, ER, EW, RR, RW>(self: Lens<A, ER, EW, RR, RW>) => Lens<A, ER, EW, Exclude<RR, R2>, Exclude<RW, R2>>
-    <E2, R2>(
-        managedRuntime: ManagedRuntime.ManagedRuntime<R2, E2>,
-    ): <A, ER, EW, RR, RW>(self: Lens<A, ER, EW, RR, RW>) => Lens<A, ER | E2, EW | E2, Exclude<RR, R2>, Exclude<RW, R2>>
-    <A, ER, EW, RR, RW, R2>(
-        self: Lens<A, ER, EW, RR, RW>,
-        runtime: Runtime.Runtime<R2>,
-    ): Lens<A, ER, EW, Exclude<RR, R2>, Exclude<RW, R2>>
-    <A, ER, EW, RR, RW, E2, R2>(
-        self: Lens<A, ER, EW, RR, RW>,
-        runtime: ManagedRuntime.ManagedRuntime<R2, E2>,
-    ): Lens<A, ER | E2, EW | E2, Exclude<RR, R2>, Exclude<RW, R2>>
-} = Function.dual(2, <A, ER, EW, RR, RW, E2, R2>(
-    self: Lens<A, ER, EW, RR, RW>,
-    runtime: Runtime.Runtime<R2>,
-) => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
-    access: parent => Effect.map(
-        Effect.provide(parent, runtime),
-        frame => ({
-            value: frame.value,
-            commit: next => Effect.provide(frame.commit(Effect.provide(next, runtime)), runtime),
-        }),
-    ),
-    transformStream: stream => Stream.unwrap(Effect.map(
-            Effect.provide(Effect.context<RR>(), runtime),
-            context => Stream.provideContext(stream, context),
-    )),
-} as LensStep<A, A, ER | E2, ER, EW | E2, EW, Exclude<RR, R2>, RR, Exclude<RW, R2>, RW>))
+    transformStream: Stream.provideSomeContext(context),
+}))
 
 /**
  * Provides a single service to a `Lens`, removing it from both the read and write environments.
@@ -706,8 +660,7 @@ export const provideService: {
     self: Lens<A, ER, EW, RR, RW>,
     tag: Context.Tag<I, S>,
     service: NoInfer<S>,
-): Lens<A, ER, EW, Exclude<RR, I>, Exclude<RW, I>> => derive(asLensImpl(self), {
-    [LensStepTypeId]: LensStepTypeId,
+): Lens<A, ER, EW, Exclude<RR, I>, Exclude<RW, I>> => derive(self, {
     access: parent => Effect.map(
         Effect.provideService(parent, tag, service),
         frame => ({
@@ -715,8 +668,8 @@ export const provideService: {
             commit: next => Effect.provideService(frame.commit(Effect.provideService(next, tag, service)), tag, service),
         }),
     ),
-    transformStream: stream => Stream.provideService(stream, tag, service),
-} as LensStep<A, A, ER, ER, EW, EW, Exclude<RR, I>, RR, Exclude<RW, I>, RW>))
+    transformStream: Stream.provideService(tag, service),
+}))
 
 
 /**