Async combinators

README.md

@@ -33,28 +33,6 @@ import { ... } from 'https://denopkg.com/Coder-Spirit/lambda-ioc@[VERSION]/lambd
 import { ... } from 'https://deno.land/x/lambda_ioc@[VERSION]/lambda-ioc/deno/index.ts'
 ```
 
-## Benefits
-
-- 100% type safe:
-  - The type checker will complain if we try to resolve unregistered
-    dependencies.
-  - The type checker will complain if we try to register new dependencies that
-    depend on unregistered dependencies, or if there is any kind of type
-    mismatch.
-- Purely functional
-- Immutable
-- Circular dependencies are impossible
-
-## Drawbacks
-
-- All dependencies must be declared "in order".
-  - This implies that this IoC container cannot be used in combination with some
-    auto-wiring solutions, such as IoC decorators.
-- The involved types are a bit convoluted:
-  - They might cause the type checker to be slow.
-  - In some situations, the type checker might be unable to infer the involved
-    types due to excessive "nested types" depth.
-
 ## Example
 
 ```ts
@@ -105,13 +83,33 @@ container.resolveGroup('group2') // ~ [3, 4], not necessarily in the same order
 ```
 
 It is also possible to register and resolve asynchronous factories and
-dependencies. They are not documented yet because some "helpers" are missing,
-and therefore it's a bit more annoying to take advantage of that feature.
-
-If you are curious, just try out:
+dependencies. If you are curious, just try out:
 - `registerAsync`
+- `registerAsyncConstructor`
 - `resolveAsync`
 
+## Benefits
+
+- 100% type safe:
+  - The type checker will complain if we try to resolve unregistered
+    dependencies.
+  - The type checker will complain if we try to register new dependencies that
+    depend on unregistered dependencies, or if there is any kind of type
+    mismatch.
+- Purely functional
+- Immutable
+- Circular dependencies are impossible
+
+## Drawbacks
+
+- All dependencies must be declared "in order".
+  - This implies that this IoC container cannot be used in combination with some
+    auto-wiring solutions, such as IoC decorators.
+- The involved types are a bit convoluted:
+  - They might cause the type checker to be slow.
+  - In some situations, the type checker might be unable to infer the involved
+    types due to excessive "nested types" depth.
+
 ## Differences respect to Diddly
 
 - First-class support for Deno.

lambda-ioc/README.md

@@ -33,28 +33,6 @@ import { ... } from 'https://denopkg.com/Coder-Spirit/lambda-ioc@[VERSION]/lambd
 import { ... } from 'https://deno.land/x/lambda_ioc@[VERSION]/lambda-ioc/deno/index.ts'
 ```
 
-## Benefits
-
-- 100% type safe:
-  - The type checker will complain if we try to resolve unregistered
-    dependencies.
-  - The type checker will complain if we try to register new dependencies that
-    depend on unregistered dependencies, or if there is any kind of type
-    mismatch.
-- Purely functional
-- Immutable
-- Circular dependencies are impossible
-
-## Drawbacks
-
-- All dependencies must be declared "in order".
-  - This implies that this IoC container cannot be used in combination with some
-    auto-wiring solutions, such as IoC decorators.
-- The involved types are a bit convoluted:
-  - They might cause the type checker to be slow.
-  - In some situations, the type checker might be unable to infer the involved
-    types due to excessive "nested types" depth.
-
 ## Example
 
 ```ts
@@ -105,13 +83,33 @@ container.resolveGroup('group2') // ~ [3, 4], not necessarily in the same order
 ```
 
 It is also possible to register and resolve asynchronous factories and
-dependencies. They are not documented yet because some "helpers" are missing,
-and therefore it's a bit more annoying to take advantage of that feature.
-
-If you are curious, just try out:
+dependencies. If you are curious, just try out:
 - `registerAsync`
+- `registerAsyncConstructor`
 - `resolveAsync`
 
+## Benefits
+
+- 100% type safe:
+  - The type checker will complain if we try to resolve unregistered
+    dependencies.
+  - The type checker will complain if we try to register new dependencies that
+    depend on unregistered dependencies, or if there is any kind of type
+    mismatch.
+- Purely functional
+- Immutable
+- Circular dependencies are impossible
+
+## Drawbacks
+
+- All dependencies must be declared "in order".
+  - This implies that this IoC container cannot be used in combination with some
+    auto-wiring solutions, such as IoC decorators.
+- The involved types are a bit convoluted:
+  - They might cause the type checker to be slow.
+  - In some situations, the type checker might be unable to infer the involved
+    types due to excessive "nested types" depth.
+
 ## Differences respect to Diddly
 
 - First-class support for Deno.

lambda-ioc/deno/combinators.ts

@@ -1,22 +1,24 @@
 import {
-  ContainerKey,
+  AsyncDependencyFactory,
   ReadableContainer,
+  ReadableSyncContainer,
   SyncDependencyFactory,
 } from './container.ts';
-import { ParamsToResolverKeys, TupleO, Zip } from './util.ts';
+import { ContainerKey, ParamsToResolverKeys, TupleO, Zip } from './util.ts';
 
 /**
  * Given a dependency factory, returns a new factory that will always resolve
  * the same instance of the dependency.
  */
 export function singleton<
   TVal,
-  TDependencies extends Record<ContainerKey, unknown>,
+  TSyncDependencies extends Record<ContainerKey, unknown>,
 >(
-  // eslint-disable-next-line @typescript-eslint/ban-types
-  factory: SyncDependencyFactory<TVal, ReadableContainer<TDependencies, {}>>,
-  // eslint-disable-next-line @typescript-eslint/ban-types
-): SyncDependencyFactory<TVal, ReadableContainer<TDependencies, {}>> {
+  factory: SyncDependencyFactory<
+    TVal,
+    ReadableSyncContainer<TSyncDependencies>
+  >,
+): SyncDependencyFactory<TVal, ReadableSyncContainer<TSyncDependencies>> {
   let result: Awaited<TVal> | undefined
 
   return (container) => {
@@ -27,6 +29,33 @@ export function singleton<
   }
 }
 
+/**
+ * Given a dependency factory, returns a new asynchronous factory that will
+ * always resolve the same instance of the dependency.
+ */
+export function asyncSingleton<
+  TVal,
+  TSyncDependencies extends Record<ContainerKey, unknown>,
+  TAsyncDependencies extends Record<ContainerKey, unknown>,
+>(
+  factory: AsyncDependencyFactory<
+    TVal,
+    ReadableContainer<TSyncDependencies, TAsyncDependencies>
+  >,
+): AsyncDependencyFactory<
+  TVal,
+  ReadableContainer<TSyncDependencies, TAsyncDependencies>
+> {
+  let result: TVal | undefined
+
+  return async (container) => {
+    if (!result) {
+      result = await factory(container)
+    }
+    return result
+  }
+}
+
 /**
  * Given a function, and a list of named dependencies, creates a new dependency
  * factory that will resolve a parameterless function wrapping the original
@@ -35,20 +64,20 @@ export function singleton<
 export function func<
   TParams extends readonly unknown[],
   TReturn,
-  TDependencies extends ParamsToResolverKeys<TParams>,
+  TSyncDependencies extends ParamsToResolverKeys<TParams>,
 >(
   fn: (...args: TParams) => Awaited<TReturn>,
-  ...args: TDependencies
+  ...args: TSyncDependencies
 ): SyncDependencyFactory<
   () => TReturn,
-  SyncFuncContainer<TParams, TDependencies>
+  SyncFuncContainer<TParams, TSyncDependencies>
 > {
-  return (container: SyncFuncContainer<TParams, TDependencies>) => {
+  return (container: SyncFuncContainer<TParams, TSyncDependencies>) => {
     const resolvedArgs = args.map((arg) =>
       container.resolve(
         // This is ugly as hell, but I did not want to apply ts-ignore
         arg as Parameters<
-          SyncFuncContainer<TParams, TDependencies>['resolve']
+          SyncFuncContainer<TParams, TSyncDependencies>['resolve']
         >[0],
       ),
     ) as unknown as TParams
@@ -89,11 +118,9 @@ export function constructor<
 type SyncFuncContainer<
   TParams extends readonly unknown[],
   TSyncDependencies extends ParamsToResolverKeys<TParams>,
-> = ReadableContainer<
+> = ReadableSyncContainer<
   TupleO<
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     Extract<Zip<TSyncDependencies, TParams>, readonly [ContainerKey, any][]>
-  >,
-  // eslint-disable-next-line @typescript-eslint/ban-types
-  {}
+  >
 >