diff --git a/src/algebra/free.js b/src/algebra/free.js
index ca81457..28c072b 100644
--- a/src/algebra/free.js
+++ b/src/algebra/free.js
@@ -2,10 +2,7 @@ import { Algebra, Foldable, Monad, Traversable } from './interfaces.js'
 import { curry } from '../..//vendor/izuna/src/index.js'
 import { Reducer } from './utilities.js'
 
-/** @import { Applicative, ApplicativeTypeRef, Apply, Chain, Comonad, Foldable as FoldableT, Functor, Monad as MonadT, Morphism, Traversable as TraversableT } from './types.js' */
-
-
-/** @import { InferredMorphism } from './types.js' */
+/** @import { Applicative, ApplicativeTypeRef, Apply, Chain, Foldable as FoldableT, Functor, Morphism, Traversable as TraversableT } from './types.js' */
 
 const kleisli = curry((f, g, x) => f(x).chain(g))
 
@@ -13,7 +10,6 @@ const kleisli = curry((f, g, x) => f(x).chain(g))
  * @template T
  * @typedef {Pure<T> | Impure<T>} Free
  */
-const Free = {}
 
 /** @template T */
 export class Pure extends Algebra(Monad, Traversable) {
@@ -188,16 +184,15 @@ const pure = x => new Pure(x)
  */
 const impure = (x, f) => new Impure(x, f)
 
-
 /**
  * @template T
  * @param {T} x
  * @returns Impure<T>
  */
 export const liftF = x => impure(x, pure)
-import { id, Identity } from './identity.js'
-import { Option, some } from './option.js'
 
-const a = liftF(1).chain(() => liftF(2)).reduce((acc, x) => acc + x, 0)
-console.log(a)
+const TypeRef = () => { }
+TypeRef.constructor.of = pure
+
+export const Free = TypeRef
 
diff --git a/src/algebra/option.js b/src/algebra/option.js
index 60d8a21..314deb7 100644
--- a/src/algebra/option.js
+++ b/src/algebra/option.js
@@ -1,23 +1,16 @@
-import { Algebra, Foldable, Monad, Monoid, Setoid } from './interfaces.js'
+import { Algebra, Foldable, Monad, Setoid } from './interfaces.js'
 
 /** @import { Morphism } from './types.js' */
 
+const Interfaces = Algebra(Setoid, Monad, Foldable)
+
 /**
  * @template T
- * @type {Some<T> | None<T>} Option
+ * @typedef {Some<T> | None<T>} Option
  */
-export class Option extends Algebra(Setoid, Monad, Foldable) {
-  /**
-   * @template T
-   * @param {T} value
-   */
-  static of(value) {
-    return Some.of(value)
-  }
-}
 
 /** @template T */
-export class Some extends Option {
+export class Some extends Interfaces {
   /** @type {T} */
   #value
 
@@ -28,15 +21,6 @@ export class Some extends Option {
     this.#value = value
   }
 
-  /**
-   * @template T
-   * @param {T} value 
-   * @returns {Some<T>}
-   */
-  static of(value) {
-    return new Some(value)
-  }
-
   /**
    * @param {Option<T>} other 
    */
@@ -88,7 +72,7 @@ export class Some extends Option {
 }
 
 /** @template T */
-export class None extends Option {
+export class None extends Interfaces {
   /**
    * @param {Option<T>} other 
    */
@@ -136,10 +120,6 @@ export class None extends Option {
   reduce(_f, init) {
     return init
   }
-
-  empty() {
-    return Option.empty()
-  }
 }
 
 /**
@@ -149,3 +129,9 @@ export class None extends Option {
 export const some = value => new Some(value)
 export const none = new None()
 
+const TypeRef = some
+TypeRef.constructor['of'] = some
+TypeRef.constructor['zero'] = none
+
+export const Option = TypeRef
+
diff --git a/src/algebra/result.js b/src/algebra/result.js
index da59344..f85dc75 100644
--- a/src/algebra/result.js
+++ b/src/algebra/result.js
@@ -1,26 +1,19 @@
-import { Algebra, Foldable, Monad, Setoid } from './interfaces.js'
+import { id, Identity } from './identity.js'
+import { Algebra, Bifunctor, Foldable, Monad, Setoid } from './interfaces.js'
 
-/** @import { Morphism } from './types.js' */
+/** @import { Apply, Chain, Functor, Bifunctor as BifunctorT, Foldable as FoldableT, Morphism, Setoid as SetoidT } from './types.js' */
+
+const Interfaces = Algebra(Setoid, Monad, Foldable, Bifunctor)
 
 /**
  * @template T, E
- * @type {Ok<T, E> | Err<T, E>} Result
+ * @typedef {Ok<T, E> | Err<T, E>} Result
  */
-export class Result extends Algebra(Setoid, Monad, Foldable) {
-  /**
-   * @template T
-   * @param {T} value 
-   * @returns {Ok}
-   */
-  static of(value) {
-    return new Ok(value)
-  }
-}
 
 /**
  * @template T, E
  */
-export class Ok extends Result {
+export class Ok extends Interfaces {
   /** @type {T} */
   #value
 
@@ -35,11 +28,14 @@ export class Ok extends Result {
   }
 
   /**
+   * @type {SetoidT<T>['equals']}
    * @param {Result<T, E>} other 
+   * @returns {boolean}
    */
   equals(other) {
-    return other instanceof Ok &&
-      other.chain(v => v === this.#value)
+    if (!(other instanceof Ok)) { return false }
+    const eq = other.chain(v => (id(v === this.#value)))
+    return /** @type {Identity<boolean>} */ (eq).extract()
   }
 
   /** @returns {this is Ok<T, E>} */
@@ -49,30 +45,38 @@ export class Ok extends Result {
   isErr() { return false }
 
   /**
-   * @template R
-   * @param {Morphism<T, R>} f 
-   * @this {Ok<T, E>}
-   * @returns {R}
+   * @type {Chain<T>['chain']}
    */
   chain(f) {
     return f(this.#value)
   }
 
   /**
-   * @template R
-   * @param {Morphism<T, R>} f 
-   * @this {Ok<T, E>}
-   * @returns {Ok<R, E>}
+   * @template U
+   * @type {Functor<T>['map']}
+   * @param {Morphism<T, U>} f 
+   * @returns {Functor<U>}
    */
   map(f) {
-    return Result.of(this.chain(f))
+    return this.chain(v => ok(f(v)))
   }
 
   /**
-   * @template R
-   * @param {Morphism<T, R>} f 
-   * @this {Ok<T, E>}
-   * @returns {Ok<R, E>}
+   * @template U
+   * @type {Apply<T>['ap']}
+   * @param {Apply<Morphism<T, U>>} b 
+   * @returns {Result<U, E>}
+   */
+  ap(b) {
+    return /** @type {Result<U, E>} */ (this.chain(v =>
+      /** @type {Chain<U>} */(b.map(f => f(v)))
+    ))
+  }
+
+  /**
+   * @template U
+   * @borrows {Result~map}
+   * @param {Morphism<T, U>} f 
    */
   then(f) {
     return this.map(f)
@@ -89,6 +93,7 @@ export class Ok extends Result {
 
   /**
    * @template U
+   * @type {FoldableT<T>['reduce']}
    * @param {(acc: U, value: T) => U} f
    * @param {U} init
    * @returns {U}
@@ -101,7 +106,7 @@ export class Ok extends Result {
 /**
  * @template T, E
  */
-export class Err extends Result {
+export class Err extends Interfaces {
   /** @type {E} */
   #value
 
@@ -115,12 +120,16 @@ export class Err extends Result {
     this.#value = value
   }
 
+
   /**
-   * @param {Result<T, E>} other 
+   * @type {SetoidT<T>['equals']}
+   * @param {Err<T, E>} other 
+   * @returns {boolean}
    */
   equals(other) {
-    return other instanceof Err &&
-      other.chain(v => v === this.#value)
+    if (!(other instanceof Err)) { return false }
+    const eq = other.catch(v => (id(v === this.#value)))
+    return /** @type {Identity<boolean>} */ (eq).extract()
   }
 
   /** @returns {this is Ok<T, E>} */
@@ -190,3 +199,7 @@ export const ok = v => new Ok(v)
  */
 export const err = e => new Err(e)
 
+const TypeRef = ok
+TypeRef.constructor['of'] = ok
+TypeRef.constructor['zero'] = err
+