From a65f139858a06dc2516cb50af8447de043b88c3b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julien=20Valverd=C3=A9?= <julien.valverde@mailo.com>
Date: Wed, 20 May 2026 17:08:40 +0200
Subject: [PATCH] Refactor

---
 packages/effect-lens/src/Lens.ts | 73 +++++++++++++++-----------------
 1 file changed, 35 insertions(+), 38 deletions(-)

diff --git a/packages/effect-lens/src/Lens.ts b/packages/effect-lens/src/Lens.ts
index b3384b7..b5ddd94 100644
--- a/packages/effect-lens/src/Lens.ts
+++ b/packages/effect-lens/src/Lens.ts
@@ -35,18 +35,24 @@ extends Lens<A, ER, EW, RR, RW> {
     readonly [LensWithInternalsTypeId]: LensWithInternalsTypeId
 
     readonly update: (a: A) => Effect.Effect<void, EW, RW>
-    readonly semaphore: Effect.Semaphore
+    readonly withLock: <A1, E1, R1>(self: Effect.Effect<A1, E1, R1>) => Effect.Effect<A1, E1, R1>
 }
 
 export const isLensWithInternals = (u: unknown): u is LensWithInternals<unknown, unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, LensWithInternalsTypeId)
 
+export const asLensWithInternals = <A, ER, EW, RR, RW>(
+    lens: Lens<A, ER, EW, RR, RW>
+): Effect.Effect<LensWithInternals<A, ER, EW, RR, RW>, never, never> => isLensWithInternals(lens)
+    ? Effect.succeed(lens as LensWithInternals<A, ER, EW, RR, RW>)
+    : Effect.die("Not a 'LensWithInternals'.")
+
 
 export declare namespace LensImpl {
     export interface Source<in out A, in out ER = never, in out EW = never, in out RR = never, in out RW = never> {
         readonly get: Effect.Effect<A, ER, RR>,
         readonly changes: Stream.Stream<A, ER, RR>,
         readonly update: (a: A) => Effect.Effect<void, EW, RW>,
-        readonly semaphore: Effect.Semaphore,
+        readonly withLock: <A1, E1, R1>(self: Effect.Effect<A1, E1, R1>) => Effect.Effect<A1, E1, R1>,
     }
 }
 
@@ -60,7 +66,7 @@ extends Pipeable.Class() implements LensWithInternals<A, ER, EW, RR, RW> {
     readonly get: Effect.Effect<A, ER, RR>
     readonly changes: Stream.Stream<A, ER, RR>
     readonly update: (a: A) => Effect.Effect<void, EW, RW>
-    readonly semaphore: Effect.Semaphore
+    readonly withLock: <A1, E1, R1>(self: Effect.Effect<A1, E1, R1>) => Effect.Effect<A1, E1, R1>
 
     constructor(
         source: LensImpl.Source<A, ER, EW, RR, RW>
@@ -70,19 +76,20 @@ extends Pipeable.Class() implements LensWithInternals<A, ER, EW, RR, RW> {
         this.get = source.get
         this.changes = source.changes
         this.update = source.update
-        this.semaphore = source.semaphore
+        this.withLock = source.withLock
     }
 
-    modifyEffect<B, E1 = never, R1 = never>(
-        f: (a: A) => Effect.Effect<readonly [B, A], E1, R1>
-    ) {
-        return this.semaphore.withPermits(1)(
-            Effect.flatMap(
-                this.get,
-                a => Effect.flatMap(f(a), ([b, next]) => Effect.as(this.update(next), b),
-            ))
-        )
-    }
+    modifyEffect = modifyEffect
+}
+
+function modifyEffect<A, B, ER = never, EW = never, E1 = never, RR = never, RW = never, R1 = never>(
+    this: LensWithInternals<A, ER, EW, RR, RW>,
+    f: (a: A) => Effect.Effect<readonly [B, A], E1, R1>,
+): Effect.Effect<B, ER | EW | E1, RR | RW | R1> {
+    return this.withLock(Effect.flatMap(
+        this.get,
+        a => Effect.flatMap(f(a), ([b, next]) => Effect.as(this.update(next), b),
+    )))
 }
 
 /**
@@ -109,18 +116,9 @@ extends Pipeable.Class() implements LensWithInternals<A, ER, EW, RR, RW> {
     get get() { return this.source.get }
     get changes() { return this.source.changes }
     get update() { return this.source.update }
-    get semaphore() { return this.source.semaphore }
+    get withLock() { return this.source.withLock }
 
-    modifyEffect<B, E1 = never, R1 = never>(
-        f: (a: A) => Effect.Effect<readonly [B, A], E1, R1>
-    ) {
-        return this.semaphore.withPermits(1)(
-            Effect.flatMap(
-                this.get,
-                a => Effect.flatMap(f(a), ([b, next]) => Effect.as(this.update(next), b),
-            ))
-        )
-    }
+    modifyEffect = modifyEffect
 }
 
 /**
@@ -164,18 +162,9 @@ extends Pipeable.Class() implements LensWithInternals<A, never, never, never, ne
             PubSub.publish(this.ref.pubsub, a),
         )
     }
-    get semaphore() { return this.ref.semaphore }
+    get withLock() { return this.ref.semaphore.withPermits(1) }
 
-    modifyEffect<B, E1 = never, R1 = never>(
-        f: (a: A) => Effect.Effect<readonly [B, A], E1, R1>
-    ) {
-        return this.semaphore.withPermits(1)(
-            Effect.flatMap(
-                this.get,
-                a => Effect.flatMap(f(a), ([b, next]) => Effect.as(this.update(next), b),
-            ))
-        )
-    }
+    modifyEffect = modifyEffect
 }
 
 /**
@@ -211,8 +200,16 @@ export const unwrap = <A, ER, EW, RR, RW, E1, R1>(
 ): Lens<A, ER | E1, EW | E1, RR | R1, RW | R1> => make({
     get: Effect.flatMap(effect, l => l.get),
     changes: Stream.unwrap(Effect.map(effect, l => l.changes)),
-    update: a => Effect.flatMap(effect, l => (l as LensWithInternals<A, ER, EW, RR, RW>).update(a))
-
+    update: a => Effect.flatMap(
+        effect,
+        l => Effect.flatMap(asLensWithInternals(l), l => l.update(a))
+    ),
+    withLock: <A2, E2, R2>(
+        effect2: Effect.Effect<A2, E2, R2>
+    ): Effect.Effect<A2, E1 | E2, R1 | R2> => Effect.flatMap(
+        effect,
+        l => Effect.flatMap(asLensWithInternals(l), l2 => l2.withLock(effect2)),
+    ),
 })
 
 /**