Error

The Error effect is both an Eval effect and a Either one with Throwable Either F on the “left” side. The idea is to represent computations which can fail, either with an exception or a failure. You can:

• create delayed computations with ok

• fail with fail(f: F) where F is the failure type

• throw an exception with exception

Other useful combinators are available:

• andFinally(last) registers an action to be executed even in case of an exception or a failure

• orElse runs an action and then run another one if the first is not successful

• whenFailed does the same thing than orElse but uses the error for action1 to decide which action to run next

When you run an Error effect you get back an Error Either A where Error is a type alias for Throwable Either Failure.

The Error object implements this effect with String as the Failure type but you are encouraged to create our own failure datatype and extend the Error[MyFailureDatatype] trait.