diff --git a/src/TraitExpressionBuilder.ts b/src/TraitExpressionBuilder.ts
index c563268..464740d 100644
--- a/src/TraitExpressionBuilder.ts
+++ b/src/TraitExpressionBuilder.ts
@@ -1,7 +1,8 @@
-import { unique } from "remeda"
-import { AbstractClass, IsEqual } from "type-fest"
+import { AbstractClass } from "type-fest"
 import { Trait, TraitTuple } from "./Trait"
 import { TraitExpression } from "./TraitExpression"
+import { SpreadSupertraits, spreadSupertraits } from "./spreadSupertraits"
+import { TraitsUnique, traitsUnique } from "./traitsUnique"
 import { Extendable, StaticMembers } from "./util"
 
 
@@ -9,56 +10,18 @@ export class TraitExpressionBuilder<
     Superclass   extends AbstractClass<object>,
     const Traits extends readonly Trait<any, any, any, any>[],
 > {
-    declare ["constructor"]: typeof TraitExpressionBuilder
-
     constructor(
         readonly expressionSuperclass:  Superclass,
         readonly expressionTraits:      Traits,
     ) {}
 
 
-    static spreadSupertraits<
-        const T extends readonly Trait<
-            TraitExpression<
-                typeof TraitExpression.NullSuperclass,
-                readonly Trait<any, any, any, any>[]
-            >,
-            any,
-            any,
-            any
-        >[]
-    >(
-        traits: T
-    ) {
-        return traits.flatMap(trait => [
-            ...trait.superExpression.traits,
-            trait,
-        ]) as readonly Trait<any, any, any, any>[] as TraitExpressionBuilder.SpreadSupertraits<T>
-    }
-
-    static traitsUnique<
-        const T extends readonly Trait<
-            TraitExpression<
-                typeof TraitExpression.NullSuperclass,
-                readonly Trait<any, any, any, any>[]
-            >,
-            any,
-            any,
-            any
-        >[]
-    >(
-        traits: T
-    ) {
-        return unique(traits) as readonly Trait<any, any, any, any>[] as TraitExpressionBuilder.TraitsUnique<T>
-    }
-
-
     extends<
         Super extends AbstractClass<object>
     >(
         superclass: Super
     ) {
-        return new this.constructor(
+        return new TraitExpressionBuilder(
             superclass,
             this.expressionTraits,
         )
@@ -80,12 +43,12 @@ export class TraitExpressionBuilder<
         Superclass,
         TraitExpressionBuilder.ExpressesReturnTypeTraits<Traits, T>
     > {
-        return new this.constructor(
+        return new TraitExpressionBuilder(
             this.expressionSuperclass,
 
-            this.constructor.traitsUnique([
+            traitsUnique([
                 ...this.expressionTraits,
-                ...this.constructor.spreadSupertraits(traits),
+                ...spreadSupertraits(traits),
             ]),
         )
     }
@@ -106,11 +69,11 @@ export class TraitExpressionBuilder<
         Superclass,
         TraitExpressionBuilder.ExpressesFirstReturnTypeTraits<Traits, T>
     > {
-        return new this.constructor(
+        return new TraitExpressionBuilder(
             this.expressionSuperclass,
 
-            this.constructor.traitsUnique([
-                ...this.constructor.spreadSupertraits(traits),
+            traitsUnique([
+                ...spreadSupertraits(traits),
                 ...this.expressionTraits,
             ]),
         )
@@ -141,44 +104,13 @@ export class TraitExpressionBuilder<
 }
 
 export namespace TraitExpressionBuilder {
-    export type SpreadSupertraits<Traits> = (
-        Traits extends readonly [
-            infer El extends Trait<any, any, any, any>,
-            ...infer Rest,
-        ]
-            ? readonly [
-                ...Trait.Supertraits<El>,
-                El,
-                ...SpreadSupertraits<Rest>,
-            ]
-            : readonly []
-    )
-
-    export type TraitsUnique<Traits> = (
-        Traits extends readonly [
-            ...infer Rest,
-            infer El extends Trait<any, any, any, any>,
-        ]
-            ? IsTraitInTupleFromRight<Rest, El> extends true
-                ? TraitsUnique<Rest>
-                : readonly [...TraitsUnique<Rest>, El]
-            : readonly []
-    )
-    type IsTraitInTupleFromRight<Traits, T> = (
-        Traits extends readonly [...infer Rest, infer El]
-            ? IsEqual<El, T> extends true
-                ? true
-                : IsTraitInTupleFromRight<Rest, T>
-            : false
-    )
-
     export type ExpressesReturnTypeTraits<
         Traits extends readonly Trait<any, any, any, any>[],
         T      extends readonly Trait<any, any, any, any>[],
     > = (
-        TraitExpressionBuilder.TraitsUnique<readonly [
+        TraitsUnique<readonly [
             ...Traits,
-            ...TraitExpressionBuilder.SpreadSupertraits<T>,
+            ...SpreadSupertraits<T>,
         ]>
     )
 
@@ -186,8 +118,8 @@ export namespace TraitExpressionBuilder {
         Traits extends readonly Trait<any, any, any, any>[],
         T      extends readonly Trait<any, any, any, any>[],
     > = (
-        TraitExpressionBuilder.TraitsUnique<readonly [
-            ...TraitExpressionBuilder.SpreadSupertraits<T>,
+        TraitsUnique<readonly [
+            ...SpreadSupertraits<T>,
             ...Traits,
         ]>
     )
diff --git a/src/effect/EffectSchemaTraitExpressionBuilder.ts b/src/effect/EffectSchemaTraitExpressionBuilder.ts
new file mode 100644
index 0000000..a67c018
--- /dev/null
+++ b/src/effect/EffectSchemaTraitExpressionBuilder.ts
@@ -0,0 +1,78 @@
+import { Schema as S } from "@effect/schema"
+import { Trait } from "../Trait"
+import { TraitExpression } from "../TraitExpression"
+import { TraitExpressionBuilder } from "../TraitExpressionBuilder"
+import { spreadSupertraits } from "../spreadSupertraits"
+import { traitsUnique } from "../traitsUnique"
+
+
+export class EffectSchemaTraitExpressionBuilder<
+    Superclass   extends S.Class<unknown, Fields, A, I, R, C, Inherited, Proto>,
+    const Traits extends readonly Trait<any, any, any, any>[],
+
+    Fields       extends S.Struct.Fields,
+    A, I, R, C,
+    Inherited    extends object,
+    Proto,
+> {
+    constructor(
+        readonly expressionSuperclass:  Superclass,
+        readonly expressionTraits:      Traits,
+    ) {}
+
+
+    extends<
+        Super          extends S.Class<unknown, SuperFields, SuperA, SuperI, SuperR, SuperC, SuperInherited, SuperProto>,
+
+        SuperFields    extends S.Struct.Fields,
+        SuperA, SuperI, SuperR, SuperC,
+        SuperInherited extends object,
+        SuperProto,
+    >(
+        superclass: Super | S.Class<unknown, SuperFields, SuperA, SuperI, SuperR, SuperC, SuperInherited, SuperProto>
+    ) {
+        return new EffectSchemaTraitExpressionBuilder<
+            Super,
+            Traits,
+
+            SuperFields,
+            SuperA, SuperI, SuperR, SuperC,
+            SuperInherited,
+            SuperProto
+        >(
+            superclass as Super,
+            this.expressionTraits,
+        )
+    }
+
+    expresses<
+        const T extends readonly Trait<
+            TraitExpression<
+                typeof TraitExpression.NullSuperclass,
+                readonly Trait<any, any, any, any>[]
+            >,
+            any,
+            any,
+            any
+        >[]
+    >(
+        ...traits: T
+    ): EffectSchemaTraitExpressionBuilder<
+        Superclass,
+        TraitExpressionBuilder.ExpressesReturnTypeTraits<Traits, T>,
+
+        Fields,
+        A, I, R, C,
+        Inherited,
+        Proto
+    > {
+        return new EffectSchemaTraitExpressionBuilder(
+            this.expressionSuperclass,
+
+            traitsUnique([
+                ...this.expressionTraits,
+                ...spreadSupertraits(traits),
+            ]),
+        )
+    }
+}
diff --git a/src/spreadSupertraits.ts b/src/spreadSupertraits.ts
new file mode 100644
index 0000000..77c3377
--- /dev/null
+++ b/src/spreadSupertraits.ts
@@ -0,0 +1,35 @@
+import { Trait } from "./Trait"
+import { TraitExpression } from "./TraitExpression"
+
+
+export function spreadSupertraits<
+    const T extends readonly Trait<
+        TraitExpression<
+            typeof TraitExpression.NullSuperclass,
+            readonly Trait<any, any, any, any>[]
+        >,
+        any,
+        any,
+        any
+    >[]
+>(
+    traits: T
+) {
+    return traits.flatMap(trait => [
+        ...trait.superExpression.traits,
+        trait,
+    ]) as readonly Trait<any, any, any, any>[] as SpreadSupertraits<T>
+}
+
+export type SpreadSupertraits<Traits> = (
+    Traits extends readonly [
+        infer El extends Trait<any, any, any, any>,
+        ...infer Rest,
+    ]
+        ? readonly [
+            ...Trait.Supertraits<El>,
+            El,
+            ...SpreadSupertraits<Rest>,
+        ]
+        : readonly []
+)
diff --git a/src/traitsUnique.ts b/src/traitsUnique.ts
new file mode 100644
index 0000000..6df91cd
--- /dev/null
+++ b/src/traitsUnique.ts
@@ -0,0 +1,39 @@
+import { unique } from "remeda"
+import { IsEqual } from "type-fest"
+import { Trait } from "./Trait"
+import { TraitExpression } from "./TraitExpression"
+
+
+export function traitsUnique<
+    const T extends readonly Trait<
+        TraitExpression<
+            typeof TraitExpression.NullSuperclass,
+            readonly Trait<any, any, any, any>[]
+        >,
+        any,
+        any,
+        any
+    >[]
+>(
+    traits: T
+) {
+    return unique(traits) as readonly Trait<any, any, any, any>[] as TraitsUnique<T>
+}
+
+export type TraitsUnique<Traits> = (
+    Traits extends readonly [
+        ...infer Rest,
+        infer El extends Trait<any, any, any, any>,
+    ]
+        ? IsTraitInTupleFromRight<Rest, El> extends true
+            ? TraitsUnique<Rest>
+            : readonly [...TraitsUnique<Rest>, El]
+        : readonly []
+)
+type IsTraitInTupleFromRight<Traits, T> = (
+    Traits extends readonly [...infer Rest, infer El]
+        ? IsEqual<El, T> extends true
+            ? true
+            : IsTraitInTupleFromRight<Rest, T>
+        : false
+)