From 1e09ca655f087a2773c24ddc8cc26f80fabd21bb Mon Sep 17 00:00:00 2001
From: rowan <rowan@kitsu.cafe>
Date: Thu, 10 Apr 2025 04:37:45 -0500
Subject: [PATCH] wip interfaces

---
 src/algebra/interfaces.js | 41 +++++++++++++----
 src/algebra/result.js     |  3 ++
 tests/units/monad.js      | 94 ++++++++++++++++++---------------------
 3 files changed, 79 insertions(+), 59 deletions(-)

diff --git a/src/algebra/interfaces.js b/src/algebra/interfaces.js
index 37c71a1..08b6b9d 100644
--- a/src/algebra/interfaces.js
+++ b/src/algebra/interfaces.js
@@ -141,13 +141,14 @@ class Method {
    * @param {Function} target 
    */
   implement(builder, target) {
-
     const impl = this.#implementation || this._defaultImplementation(builder.name)
 
     this._getInstallationPoint(target)[this.#name] = impl
   }
 }
 
+const Implementations = Symbol()
+
 class Interface {
   #name
 
@@ -166,6 +167,27 @@ class Interface {
     return this.#name
   }
 
+  findInterfaces() {
+    let interfaces = new Set()
+    let current = Object.getPrototypeOf(this)
+    console.log(current)
+
+    while (current != null) {
+      interfaces = new Set(current[Implementations])
+      current = Object.getPrototypeOf(this)
+    }
+
+    return interfaces
+  }
+
+  /**
+   * @param {{ name: string }} type 
+   * @returns {boolean}
+   */
+  implementedBy(type) {
+    return this.findInterfaces().has(type)
+  }
+
   /**
    * @param {...(PropertyKey | Method)} methods
    * @returns {this}
@@ -200,23 +222,24 @@ class Interface {
    * @param {FunctionConstructor} base
    */
   build(base) {
-    const interfaces = [...this.#interfaces.values()].map(x => x.intoWrapper())
+    const interfaces = [...this.#interfaces.values()]
+    const wrappers = interfaces.map(x => x.intoWrapper())
 
-    const Interfaces = mix(base).with(...interfaces)
+    const Interfaces = mix(base).with(...wrappers)
 
-    const Algebra = class extends Interfaces { }
+    //const Algebra = class extends Interfaces { }
 
     for (const method of this.#methods) {
-      method.implement(this, Algebra)
+      method.implement(this, Interfaces)
     }
 
-    return Algebra
+    Interfaces.prototype[Implementations] = new Set([...interfaces])
+
+    return Interfaces
   }
 }
 
-/** @template T */
-export class BaseSet {
-}
+export class BaseSet { }
 
 /**
  * @param {PropertyKey} key
diff --git a/src/algebra/result.js b/src/algebra/result.js
index 16ce285..aef2458 100644
--- a/src/algebra/result.js
+++ b/src/algebra/result.js
@@ -19,6 +19,9 @@ export class Ok extends Algebra(Setoid, Monad, Foldable) {
     this.#value = value
   }
 
+  /**
+   * @param {Ok<T, E>} other 
+   */
   equals(other) {
     return other instanceof Ok &&
       other.chain(v => v === this.#value)
diff --git a/tests/units/monad.js b/tests/units/monad.js
index e052733..6ce7ed4 100644
--- a/tests/units/monad.js
+++ b/tests/units/monad.js
@@ -1,74 +1,68 @@
+// @ts-nocheck
 import { it, assert } from 'folktest'
 import { Option, Result } from '../../src/index.js'
+import { Chain, Ord, Setoid } from '../../src/algebra/interfaces.js'
 
-const Monads = [Option, Result]
+const Algebra = [Option, Result]
 
-const leftIdentity = (M, a, f) => {
-  assert(M(a).chain(f).equals(f(a)))
-}
+const inc = x => F.of(x + 1)
+const dbl = x => F.of(x * 2)
 
-const rightIdentity = (M, m) => {
-  assert(m.chain(M).equals(m))
-}
-
-const associativity = (m, f, g) => {
-  assert(m.chain(f).chain(g).equals(m.chain(x => f(x).chain(g))))
-}
-
-export const prove = (M, m, a, f, g) => {
-  leftIdentity(M, a, f)
-  rightIdentity(M, m)
-  associativity(m, f, g)
-}
-
-const inc = F => x => F.of(x + 1)
-const dbl = F => x => F.of(x * 2)
+const impl = i => m => i.implementedBy(m)
 
 export const Tests = [
   it('unit is a left identity', () => {
-    Monads.forEach(monad => {
-      const f = inc(monad)
-      // NOTE: okay but like, shut up
-      // @ts-ignore
-      assert(monad.of(1).chain(f).equals(f(1)))
+    console.log(Chain.implementedBy(Result))
+    Algebra.filter(impl(Chain)).forEach(algebra => {
+      assert(
+        algebra.of(1).chain(inc) == inc(1),
+        `${algebra.name} is not a left identity`
+      )
     })
-    //prove(
-    //  Ctr, M
-    //  Ctr(1), m
-    //  1, a
-    //  x => Ctr(x + 1), f
-    //  x => Ctr(x * 2) g
-    //)
   }),
 
   it('unit is a right identity', () => {
-    Monads.forEach(monad => {
-      const m = monad.of(1)
+    Algebra.filter(impl(Chain)).forEach(algebra => {
+      const m = algebra.of(1)
 
       assert(
-        // NOTE: i heard this one already
-        // @ts-ignore
-        m.chain(monad.of).equals(m)
+        m.chain(algebra.of).equals(m),
+        `${algebra.name} is not a right identity`
       )
     })
   }),
 
   it('unit is associative', () => {
-    Monads.forEach(monad => {
-      const m = monad.of(1)
-      const f = inc(monad)
-      const g = dbl(monad)
-      console.log(m.chain(f))
+    Algebra.filter(impl(Chain)).forEach(algebra => {
+      const a = algebra.of(1)
 
-      // NOTE: it was better the first time
-      // @ts-ignore
-      const x = m.chain(f).chain(g)
-      // @ts-ignore
-      const y = m.chain(x => f(x).chain(g))
+      const x = a.chain(inc).chain(dbl)
+      const y = a.chain(x => inc(x).chain(dbl))
 
-      assert(
-        x.equals(y)
-      )
+      assert(x == y, `${algebra.name} is not associative`)
+    })
+  }),
+
+  it('unit is reflexive', () => {
+    Algebra.filter(impl(Setoid)).forEach(algebra => {
+      const a = algebra.of(1)
+      assert(a.equals(a), `${algebra.name} is not reflexive`)
+    })
+  }),
+
+  it('unit is symmetrical', () => {
+    Algebra.filter(impl(Setoid)).forEach(algebra => {
+      const a = algebra.of(1)
+      const b = algebra.of(1)
+      assert(a.equals(b) && b.equals(a), `${algebra.name} is not symmetrical`)
+    })
+  }),
+
+  it('unit is antisymmetrical', () => {
+    Algebra.filter(impl(Ord)).forEach(algebra => {
+      const a = algebra.of(1)
+      const b = algebra.of(1)
+      assert(a.lte(b) && b.lte(a) && a.equals(b))
     })
   })
 ]