If you are already familiar with using the IO types in Haskell or Scala, this cheat sheet should help you get up to speed with Effective.ts quickly.
| Description | Effective.ts | Haskell | Cats Effect (Scala) |
|---|---|---|---|
| Run an action (not pure) | a.run() |
unsafePerformIO a |
.a.unsafeRunSync() |
| Defer an effect | IO(() => f()) |
IO(f()) |
|
| Wrap a pure value in IO | IO.wrap(v) |
return v |
IO.pure(v) |
| Raise an error | IO.raise(e) |
ioError e |
IO.raiseError(e) |
| Succeed with no result | IO.void |
return () |
IO.unit |
| Sequence two dependent actions, giving the result of the second | a.andThen(b) |
a >>= b |
a.flatMap(b) |
| Sequence two dependent actions, giving the result of the first | a.through(b) |
a >>= \x -> b x <$ x |
a.flatTap(b) |
| Replace the result of an action | a.as(v) |
a <$ v |
a.as(v) |
| Transform the result of an action | a.map(f) |
fmap f a |
a.map(f) |
| Catch a raised error | a.catch(e => handle(e)) |
catchIOError a \e -> handle e |
a.handleErrorWith(e => handle(e)) |
| Transform a raised error | a.mapError(f) |
modifyIOError f a |
a.adaptError(f) |
| Pause execution for 1 second | IO.wait(1, "second") |
threadDelay 1000000 |
IO.sleep(1.seconds) |
| Cancel the current fiber | IO.cancel() |
IO.canceled |
|
| Combine two independent actions in parallel | IO.parallel([a, b]) |
concurrently a b |
(a, b).parTupled |
| Combine two independent actions in series | a.andThen(() => b) |
a *> b |
a *> b |
| Race two actions against each other | IO.race([a, b]) |
race a b |
IO.race(a, b) |