Confusion with Curried APIs in Effect Library

import { Effect } from "effect"

const myfunc = Effect.fn("myspan")(function* <N extends number>(n: N) {
  yield* Effect.annotateCurrentSpan("n", n)
  console.log(`got: ${n}`)
  yield* Effect.fail(new Error("Boom!"))
})

// Without examples, I would have expected this:
Effect.fn({ span: "myspan", gen: function*() {} })

class OpenAiError extends Data.TaggedClass("OpenAiError")<{
  cause: unknown
}> {}

// Without examples, I would have expected this:
class OpenAiError extends Data.TaggedClass({ _tag: "OpenAiError" }){}

class OpenAiError extends Schema.TaggedError<OpenAiError>()("OpenAiError", {
  cause: Schema.Defect
}){}

// Just very confused why the currying method was rearranged compared to example 2. Especially since the first curry is empty parentheses (), so nothing is being curried.

export const wrapWithMySpan = Effect.fn("myspan");
//...
wrapWithMySpan(function* gen1() {})
//...
wrapWithMySpan(function* gen2() {})