Fixed error detection

src/expresses.ts

@@ -6,18 +6,24 @@ import { ExtendFn, ExtendableFn, SimplifyFn, StaticMembersFn } from "./util"
 
 class TraitExpression<
     Super  extends AbstractClass<any>,
-    Traits extends readonly Trait<any, any>[],
+    Traits extends Trait<any, any>[],
 > {
     constructor(
         readonly superclass:  Super,
         readonly traits:      Traits,
     ) {}
 
-    get implements() {
-        return {}
+    get implements(): (
+        Pipe<Traits, [
+            Tuples.Map<TraitAbstractMembersFn>,
+            ExtendFn,
+            SimplifyFn,
+        ]>
+    ) {
+        throw new Error("Not meant to be called")
     }
 
-    extends(): (
+    get extends(): (
         AbstractClass<
             Pipe<[
                 InstanceType<Super>,
@@ -59,7 +65,7 @@ export type Implements<Exp extends TraitExpression<any, any>> = (
 
 class TraitExpressionBuilder<
     Super  extends AbstractClass<any>,
-    Traits extends readonly Trait<any, any>[],
+    Traits extends Trait<any, any>[],
 > {
     constructor(public expression: TraitExpression<Super, Traits>) {}
 
@@ -75,7 +81,7 @@ class TraitExpressionBuilder<
     }
 
     expresses<
-        AppendTraits extends readonly Trait<any, any>[]
+        AppendTraits extends Trait<any, any>[]
     >(...traits: AppendTraits) {
         return new TraitExpressionBuilder(
             new TraitExpression(
@@ -89,15 +95,15 @@ class TraitExpressionBuilder<
         return this.expression as GetTraitExpression<Super, Traits>
     }
 
-    then<V>(fn: (expression: typeof this.expression) => V): V {
-        return fn(this.expression)
+    then<V>(fn: (expression: ReturnType<typeof this.get>) => V): V {
+        return fn(this.get())
     }
 }
 
 
 type AbstractMembersExtendable<
     Super  extends AbstractClass<any>,
-    Traits extends readonly Trait<any, any>[],
+    Traits extends Trait<any, any>[],
 > = (
     Call<ExtendableFn, [
         InstanceType<Super>,
@@ -107,7 +113,7 @@ type AbstractMembersExtendable<
 
 type ImplInstanceExtendable<
     Super  extends AbstractClass<any>,
-    Traits extends readonly Trait<any, any>[],
+    Traits extends Trait<any, any>[],
 > = (
     Call<ExtendableFn, [
         InstanceType<Super>,
@@ -117,7 +123,7 @@ type ImplInstanceExtendable<
 
 type ImplStaticMembersExtendable<
     Super  extends AbstractClass<any>,
-    Traits extends readonly Trait<any, any>[],
+    Traits extends Trait<any, any>[],
 > = (
     Pipe<[
         Super,
@@ -130,7 +136,7 @@ type ImplStaticMembersExtendable<
 
 type GetTraitExpression<
     Super  extends AbstractClass<any>,
-    Traits extends readonly Trait<any, any>[],
+    Traits extends Trait<any, any>[],
 > = (
     Call<Tuples.IsEmpty, Traits> extends true
         ? "Cannot express an empty list of traits."

src/tests.ts

@@ -1,3 +1,4 @@
+import { Identity, Pipe, Tuples } from "hotscript"
 import { Implements, TraitAbstractMembers, expression, trait } from "."
 
 
@@ -51,17 +52,14 @@ class TestSuperclass {
 const builder = expression
     .extends(TestSuperclass)
     .expresses(
-        // PrintsHelloOnNew,
+        PrintsHelloOnNew,
         Identifiable<bigint>(),
         // Identifiable<number>(),
     )
 
-type Impl = Implements<typeof builder.expression>
-
-
 const exp = builder.get()
 
-class User extends exp.extends() implements (typeof exp.implements) {
+class User extends exp.extends implements (typeof exp.implements) {
     // id: bigint = -1n
 }
 

src/util/extend.ts

@@ -13,7 +13,7 @@ interface ExtendReducerFn extends Fn {
 }
 
 export type ExtendFn = Tuples.Reduce<ExtendReducerFn, {}>
-export type Extend<T extends readonly object[]> = Call<ExtendFn, T>
+export type Extend<T extends object[]> = Call<ExtendFn, T>
 
 
 export type ExtendableFn = ComposeLeft<[
@@ -23,4 +23,4 @@ export type ExtendableFn = ComposeLeft<[
         Match.With<any, true>,
     ]>
 ]>
-export type Extendable<T extends readonly object[]> = Call<ExtendableFn, T>
+export type Extendable<T extends object[]> = Call<ExtendableFn, T>