Understanding the `modify` Function Signature in TypeScript

shaugh · 2024-10-24T21:01:55.519Z

Why is the signature for `modify` ` (f: (a: A) => readonly [B, A]): (self: Ref ) => Effect.Effect `? What is the `A` in `[B, A]` for?

Why is the signature for

modify

modify

<A, B>(f: (a: A) => readonly [B, A]): (self: Ref<A>) => Effect.Effect<B>

<A, B>(f: (a: A) => readonly [B, A]): (self: Ref<A>) => Effect.Effect<B>

? What is the

[B, A]

[B, A]

for?

Understanding the `modify` Function Signature in TypeScript - Effect Community