Effect Core

The Effect type in Effect-TS is a description of a computation that succeeds or fails, meaning it does not execute until you explicitly run it. This allows you to compose synchronous and asynchronous operations declaratively before runtime execution.

To create an Effect-TS program, use Effect.succeed or Effect.fail for synchronous values and Effect.promise for asynchronous operations. You then execute these effects using runtime methods like Effect.runSync or Effect.runPromise to observe the final result.

Generator syntax with Effect.gen composes effects sequentially in Effect-TS by yielding results step by step. This approach provides readable, linear code flow for chaining multiple synchronous and asynchronous operations without deep nested callbacks.

Yes, you need TypeScript to effectively use Effect-TS core composition and runtime APIs. The framework relies heavily on TypeScript's type system to manage the Effect<Success, Error, Requirements> type and ensure typed errors throughout your functional workflows.

The best way to handle errors in Effect-TS is to use typed errors with Effect.fail instead of throwing exceptions. This ensures your error channels are explicitly typed within the Effect<Success, Error, Requirements> signature for predictable runtime execution.

You should use Effect.runSync to execute synchronous Effect-TS programs immediately, and Effect.runPromise when your program involves asynchronous operations via Effect.promise. Both runtime methods trigger the actual execution of your composed effects to produce a result.