TraitsUniq

src/TraitExpressionBuilder.ts

@@ -1,5 +1,5 @@
 import { uniq } from "lodash-es"
-import { AbstractClass } from "type-fest"
+import { AbstractClass, IsEqual } from "type-fest"
 import { Trait, TraitTuple } from "./Trait"
 import { TraitExpression } from "./TraitExpression"
 import { Extendable, StaticMembers } from "./util"
@@ -15,6 +15,21 @@ type SpreadSupertraits<T> = (
         : []
 )
 
+type TraitsUniq<Traits> = (
+    Traits extends [...infer Rest, infer Trait]
+        ? IsTraitInTupleFromRight<Rest, Trait> extends true
+            ? TraitsUniq<Rest>
+            : [...TraitsUniq<Rest>, Trait]
+        : []
+)
+type IsTraitInTupleFromRight<Traits, T> = (
+    Traits extends [...infer Rest, infer Trait]
+        ? IsEqual<Trait, T> extends true
+            ? true
+            : IsTraitInTupleFromRight<Rest, T>
+        : false
+)
+
 
 type BuildTraitExpression<
     Superclass extends AbstractClass<object>,
@@ -80,7 +95,7 @@ export class TraitExpressionBuilder<
                     ...trait.superExpression.traits,
                     trait,
                 ]),
-            ]) as [...Traits, ...SpreadSupertraits<T>],
+            ]) as TraitsUniq<[...Traits, ...SpreadSupertraits<T>]>,
         )
     }
 

src/tests.ts

@@ -81,9 +81,3 @@ class User extends exp.extends implements Implements<typeof exp> {
 }
 
 console.log(new User())
-
-
-// type T = NonExtendableKeys<[
-//     { prout: "gneugneu" },
-//     { prout: string },
-// ]>