Deferred as Effect

SandroMaglione · Mar 27, 2024 · ac7f9e1 · ac7f9e1
1 parent e4d3ad2
commit ac7f9e1
Show file tree

Hide file tree

Showing 3 changed files with 13 additions and 3 deletions.
diff --git a/packages/fpdart/example/main.dart b/packages/fpdart/example/main.dart
@@ -10,5 +10,6 @@ final option = Some(10);
 final effect = Effect<Env, Error, Success>.gen(($) {
   final eitherValue = $.sync(either);
   final optionValue = $.sync(option);
+  final deferred = $.sync(Deferred<Error, Success>());
   return eitherValue + optionValue;
 });
diff --git a/packages/fpdart/lib/src/deferred.dart b/packages/fpdart/lib/src/deferred.dart
@@ -1,6 +1,6 @@
 part of 'effect.dart';
 
-final class Deferred<L, R> extends IEffect<Null, L, R> {
+final class Deferred<L, R> extends IEffect<Never, L, Option<R>> {
   Option<Exit<L, R>> _value = None();
 
   Completer<Exit<L, R>>? __completer;
@@ -17,8 +17,14 @@ final class Deferred<L, R> extends IEffect<Null, L, R> {
   bool get unsafeCompleted => _value is Some<Exit<L, R>>;
 
   @override
-  Effect<Null, L, R> get asEffect => Effect.from(
-        (_) => await<Null>()._unsafeRun(Context.env(null)),
+  Effect<Never, L, Option<R>> get asEffect => Effect.from(
+        (_) => switch (_value) {
+          None() => Right(None()),
+          Some(value: final exit) => switch (exit) {
+              Left() => Right(None()),
+              Right(value: final value) => Right(Some(value)),
+            },
+        },
       );
 
   Effect<E, L, R> await<E>() => Effect.from(

diff --git a/packages/fpdart/lib/src/effect.dart b/packages/fpdart/lib/src/effect.dart
@@ -618,6 +618,9 @@ final class Effect<E, L, R> extends IEffect<E, L, R> {
   /// {@category delay}
   Effect<E, L, R> timeout(Duration duration) =>
       race(Effect<E, L, R>.failCause(const Interrupted()).delay(duration));
+
+  /// {@category interruption}
+  Effect<E, Never, R> interrupt() => Effect.failCause(const Interrupted());
 }
 
 extension ProvideNull<L, R> on Effect<Null, L, R> {