src/expresses.ts

@@ -1,84 +1,50 @@
 import { AbstractClass, Opaque } from "type-fest"
 import { Trait, TraitApplierSuperTag } from "."
-import { ClassesInstances, ClassesStaticMembers, MergeInheritanceTree, MergeInheritanceTreeWithoutOverriding, StaticMembers, TraitsClasses } from "./util"
+import { MergeInheritanceTree, TraitsAbstractMembers } from "./util"
+
+
+class TraitsExpression<
+    Super  extends AbstractClass<any>,
+    Traits extends readonly Trait<any, any>[],
+> {
+    constructor(
+        readonly superclass:  Super,
+        readonly traits:      Traits,
+    ) {}
+
+    implements(): (
+        MergeInheritanceTree<
+            TraitsAbstractMembers<Traits>
+        >
+    ) {
+        return {} as any
+    }
+
+    extends() {
+        return this.traits.reduce(
+            (previous, trait) => trait.apply(previous),
+            this.superclass as Opaque<Super, TraitApplierSuperTag>,
+        )
+    }
+}
 
 
-/**
- * Extends a class with the given traits and expresses their combined functionality.
- * @template C - The abstract class type.
- * @template Traits - An array of traits.
- * @param extend - The class to extend.
- * @param traits - An array of traits to apply.
- * @returns A new class type expressing the combined functionality of the base class and traits.
- * @example
- * Extends a superclass and applies traits:
- * ```ts
- * class User extends extendsAndExpresses(Entity,
- *     Identifiable<bigint>(),
- *     Permissible,
- * ) {
- *     readonly id: bigint
- *
- *     constructor(id: bigint) {
- *         super()
- *         this.id = id
- *     }
- * }
- * ```
- */
 export function extendsAndExpresses<
-    C      extends AbstractClass<any>,
+    Super  extends AbstractClass<any>,
-    Traits extends readonly Trait<any>[],
+    Traits extends readonly Trait<any, any>[],
 >(
-    extend: C,
+    superclass:  Super,
-    ...traits: Traits
+    ...traits:   Traits
 ) {
-    return traits.reduce(
+    return new TraitsExpression(superclass, traits)
-        (previous, trait) => trait(previous),
-        extend as Opaque<C, TraitApplierSuperTag>,
-    ) as unknown as (
-        AbstractClass<
-            MergeInheritanceTreeWithoutOverriding<[
-                InstanceType<C>,
-                ...ClassesInstances<
-                    TraitsClasses<Traits>
-                >,
-            ]>,
-
-            ConstructorParameters<C>
-        > &
-
-        MergeInheritanceTree<[
-            StaticMembers<C>,
-            ...ClassesStaticMembers<
-                TraitsClasses<Traits>
-            >,
-        ]>
-    )
 }
 
-/**
+class DefaultSuperclass {}
- * Expresses the combined functionality of multiple traits.
+
- * @template Traits - An array of trait.
- * @param traits - An array of trait to apply.
- * @returns A new class type expressing the combined functionality of the traits.
- * @example
- * Applies traits to a class:
- * ```ts
- * class User extends expresses(Identifiable<bigint>(), Permissible) {
- *     readonly id: bigint
- *
- *     constructor(id: bigint) {
- *         super()
- *         this.id = id
- *     }
- * }
- * ```
- */
 export function expresses<
-    Traits extends readonly Trait<any>[],
+    Traits extends readonly Trait<any, any>[],
 >(
     ...traits: Traits
 ) {
-    return extendsAndExpresses(Object, ...traits)
+    return new TraitsExpression(DefaultSuperclass, traits)
 }

src/tests.ts

@@ -1,4 +1,4 @@
-import { trait } from "."
+import { expresses, trait } from "."
 
 
 const PrintsHelloOnNew = trait()(Super =>
@@ -10,11 +10,17 @@ const PrintsHelloOnNew = trait()(Super =>
     }
 )
 
-const Identifiable = <ID>() =>
+const Identifiable = <ID>() => (
-    trait<{ id: ID }>()(Super =>
+    trait<{ readonly id: ID }>()(Super =>
         class Identifiable extends Super {
             equals(el: Identifiable) {
                 return this.id === el.id
             }
         }
     )
+)
+
+
+const exp = expresses(Identifiable<bigint>())
+
+class User implements typeof exp.implements()

src/trait.ts

@@ -42,8 +42,32 @@ export type Trait<
     }, TraitTag>
 )
 
+export type TraitAbstractMembers<T> = (
+    T extends Trait<infer AbstractMembers, any>
+        ? AbstractMembers
+        : never
+)
 
-export type TraitApplierSuperTag = "@thilawyn/traitify-ts/Super"
+export type TraitImpl<T> = (
+    T extends Trait<any, infer Impl>
+        ? Impl
+        : never
+)
+
+export type TraitClass<T> = (
+    T extends Trait<infer AbstractMembers, infer Impl>
+        ? AddAbstractMembersToImpl<Impl, AbstractMembers>
+        : never
+)
+
+export type TraitInstance<T> = (
+    T extends Trait<infer AbstractMembers, infer Impl>
+        ? InstanceType<Impl> & AbstractMembers
+        : never
+)
+
+
+export type TraitApplierSuperTag = "@thilawyn/traitify-ts/TraitApplierSuper"
 
 export type TraitApplier<
     AbstractMembers         extends object,
@@ -54,7 +78,6 @@ export type TraitApplier<
     )
 )
 
-
 export function trait<
     AbstractMembers extends object = {}
 >(): (

src/util/trait.ts

@@ -1,14 +1,20 @@
-import { Trait, TraitClass } from ".."
+import { Trait, TraitAbstractMembers, TraitClass } from ".."
 
 
-/**
+export type TraitsAbstractMembers<Traits extends readonly Trait<any, any>[]> = (
- * Represents an array of classes corresponding to the provided traits.
- * @template Traits - An array of traits extending Trait<any>.
- */
-export type TraitsClasses<Traits extends readonly Trait<any>[]> = (
     Traits extends [infer T, ...infer Rest]
-        ? T extends Trait<any>
+        ? T extends Trait<any, any>
-            ? Rest extends Trait<any>[]
+            ? Rest extends Trait<any, any>[]
+                ? [TraitAbstractMembers<T>, ...TraitsClasses<Rest>]
+                : never
+            : never
+        : []
+)
+
+export type TraitsClasses<Traits extends readonly Trait<any, any>[]> = (
+    Traits extends [infer T, ...infer Rest]
+        ? T extends Trait<any, any>
+            ? Rest extends Trait<any, any>[]
                 ? [TraitClass<T>, ...TraitsClasses<Rest>]
                 : never
             : never