packages/effect-fc/src/Lens.ts

@@ -1,4 +1,4 @@
-import { Effect, Pipeable, Predicate, Readable, Stream, Subscribable, SubscriptionRef } from "effect"
+import { Effect, Pipeable, Predicate, Readable, Stream, Subscribable, type SubscriptionRef } from "effect"
 import * as Writable from "./Writable.js"
 
 
@@ -24,17 +24,23 @@ export const LensPrototype: LensPrototype = Object.freeze({
 
 export const isLens = (u: unknown): u is Lens<unknown, unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, LensTypeId)
 
-export const make = <A, ER, RR, EW, RW>(options: {
+export const make = <A, ER, RR, EW, RW>(
-    readonly get: Effect.Effect<A, ER, RR>
+    options: {
-    readonly changes: Stream.Stream<A, ER, RR>
+        readonly get: Effect.Effect<A, ER, RR>
-    readonly set: (value: A) => Effect.Effect<void, EW, RW>
+        readonly changes: Stream.Stream<A, ER, RR>
-}): Lens<A, ER, RR, EW, RW> => Object.setPrototypeOf({
+    } & (
+        | { readonly modify: <B>(f: (a: A) => readonly [B, A]) => Effect.Effect<B, EW, RW> }
+        | { readonly set: (value: A) => Effect.Effect<void, EW, RW> }
+    )
+): Lens<A, ER, RR, EW, RW> => Object.setPrototypeOf({
     get: options.get,
     changes: options.changes,
-    modify: <B>(f: (a: A) => readonly [B, A]) => Effect.flatMap(options.get, a => {
+    modify: Predicate.hasProperty(options, "modify")
-        const [b, next] = f(a)
+        ? options.modify
-        return Effect.map(options.set(next), () => b)
+        : <B>(f: (a: A) => readonly [B, A]) => Effect.flatMap(options.get, a => {
-    }),
+            const [b, next] = f(a)
+            return Effect.map(options.set(next), () => b)
+        }),
 }, LensPrototype)
 
 /**
@@ -45,7 +51,7 @@ export const fromSubscriptionRef = <A>(
 ): Lens<A, never, never, never, never> => make({
     get: ref.get,
     changes: ref.changes,
-    set: (v: A) => SubscriptionRef.set(ref, v),
+    modify: ref.modify,
 })
 
 export const unwrap = <A, ER, RR, EW, RW, E1, R1>(