diff --git a/types/assoc.d.ts b/types/assoc.d.ts
index cebbd9d..1a9a49c 100644
--- a/types/assoc.d.ts
+++ b/types/assoc.d.ts
@@ -1,97 +1,61 @@
 import { Placeholder } from './util/tools';
 
 // assoc(prop)
-export function assoc<K extends string>(prop: K): {
-  // assoc(prop)(val)
+export function assoc<K extends PropertyKey>(prop: K): {
+  // assoc(prop)(val)(obj)
   <T>(val: T): {
-    // assoc(prop)(val)(obj) when obj has key prop and val is typeof obj[prop]
-    <U extends Record<K, T>>(obj: U): U;
-    // assoc(prop)(val)(obj) when obj has key prop and val is not typeof obj[prop]
-    <U extends Record<K, any>>(obj: U): Record<K, T> & Omit<U, K>;
-    // assoc(prop)(val)(obj) when obj does not have key prop
-    <U>(obj: U): U & Record<K, T>;
+    <U>(obj: U): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
   }
 
-  // assoc(prop)(__, obj) when prop is keyof obj
-  <U extends Record<K, any>>(__: Placeholder, obj: U): {
-    // assoc(prop)(__, obj)(val) if val is typeof obj[prop]
-    <T extends U[K]>(val: T): U;
-    // assoc(prop)(__, obj)(val) if val is not typeof obj[prop]
-    <T>(val: T): Record<K, T> & Omit<U, K>;
+  // assoc(prop)(__, obj)(val)
+  <U>(__: Placeholder, obj: U): {
+    <T>(val: T): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
   }
-  // assoc(prop)(__, obj) when prop is not keyof obj
-  <U>(__: Placeholder, obj: U): <T>(val: T) => U & Record<K, T>;
 
-  // assoc(prop)(val, obj) when obj has key prop, tests if val is typeof obj[prop] for best return type
-  <T, U extends Record<K, any>>(val: T, obj: U): U[K] extends T ? U : Record<K, T> & Omit<U, K>;
-  // assoc(prop)(val, obj) when obj does not have a key prop
-  <T, U>(val: T, obj: U): U & Record<K, T>;
+  // assoc(prop)(val, obj)
+  <T, U>(val: T, obj: U): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
 };
 
 // assoc(__, val)
 export function assoc<T>(__: Placeholder, val: T) : {
-  // assoc(__, val)(prop)
-  <K extends string>(prop: K): {
-    // assoc(__, val)(prop)(obj) when obj has key prop, tests if val is typeof obj[prop] for best return type
-    <U extends Record<K, any>>(obj: U): U[K] extends T ? U : Record<K, T> & Omit<U, K>;
-    // assoc(__, val)(prop)(obj) when obj does not have key prop
-    <U>(obj: U): U & Record<K, T>;
+  // assoc(__, val)(prop)(obj)
+  <K extends PropertyKey>(prop: K): {
+    <U>(obj: U): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
   }
 
-  // assoc(__, val)(__, obj)
+  // assoc(__, val)(__, obj)(prop)
   <U>(__2: Placeholder, obj: U): {
-    // assoc(__, val)(__, obj)(prop), prop is keyof obj, tests if val is typeof obj[prop] for best return type
-    <K extends keyof U>(prop: K): U[K] extends T ? U : Record<K, T> & Omit<U, K>;
-    // assoc(__, val)(__, obj)(prop), prop is not keyof obj
-    <K extends string>(prop: K): U & Record<K, T>;
+    <K extends PropertyKey>(prop: K): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
   };
-  // assoc(__, val)(prop, obj), when obj has key prop, tests if val is typeof obj[prop] for best return type
-  <K extends keyof U, U>(prop: K, obj: U): U[K] extends T ? U : Record<K, T> & Omit<U, K>;
-  // assoc(__, val)(prop, obj), when obj does not have key prop
-  <K extends string, U>(prop: K, obj: U): U & Record<K, T>;
+
+  // assoc(__, val)(prop, obj)
+  <K extends PropertyKey, U>(prop: K, obj: U): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
 };
 
-// assoc(prop, val)
-export function assoc<T, K extends string>(prop: K, val: T) : {
-  // assoc(prop, val)(obj), when obj has key prop, tests if val is typeof obj[prop] for best return type
-  <U extends Record<K, any>>(obj: U): U[K] extends T ? U : Record<K, T> & Omit<U, K>;
-  // assoc(prop, val)(obj), when obj does not have key prop
-  <U>(obj: U): U & Record<K, T>;
+// assoc(prop, val)(obj)
+export function assoc<T, K extends PropertyKey>(prop: K, val: T): {
+  <U>(obj: U): U extends Record<K, any> ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
 };
 
 // assoc(__, __, obj)
 export function assoc<U>(__: Placeholder, __2: Placeholder, obj: U): {
-  // assoc(__, __, obj)(key)
-  <K extends keyof U>(key: K): {
-    // assoc(__, __, obj)(key)(value), when K is keyof U and value types match
-    <T extends U[K]>(val: T): U;
-    // assoc(__, __, obj)(key)(value), when K is keyof U and value types do not match
-    <T>(val: T): Record<K, T> & Omit<U, K>
+  // assoc(__, __, obj)(key)(val)
+  <K extends PropertyKey>(key: K): {
+    <T>(val: T): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
   }
-  // assoc(__, __, obj)(key)(value), when K is not keyof U
-  <K extends string>(key: K): <T>(val: T) => U & Record<K, T>;
-  // assoc(__, __, obj)(__, value)
+  // assoc(__, __, obj)(__, value)(key)
   <T>(__: Placeholder, val: T): {
-    // assoc(__, __, obj)(__, value)(key), when obj has key prop, tests if val is typeof obj[prop] for best return type
-    <K extends keyof U>(key: K): U[K] extends T ? U : Record<K, T> & Omit<U, K>;
-    // assoc(__, __, obj)(__, value)(key) when obj does not have key prop
-    <K extends string>(key: K): U & Record<K, T>;
+    <K extends PropertyKey>(key: K): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
   }
   // assoc(__, __, obj)(key, value)
-  <K extends keyof U>(key: K, val: U[K]): U;
-  <K extends keyof U, T>(key: K, val: T): Record<K, T> & Omit<U, K>;
-  <K extends string, T>(key: K, val: T): U & Record<K, T>;
+  <K extends PropertyKey, T>(key: K, val: T): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
 };
 
-// assoc(__, val, obj)(prop), this tests if prop is keyof obj and if val is typeof obj[prop] for best return type
-export function assoc<T, U>(__: Placeholder, val: T, obj: U): <K extends string>(prop: K) => K extends keyof U ? T extends U[K] ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
-// assoc(prop, __, obj)(val), when K is keyof obj, tests if val is typeof obj[prop] for best return type
-export function assoc<U, K extends keyof U>(prop: K, __: Placeholder, obj: U): <T>(val: T) => T extends U[K] ? U : Record<K, T> & Omit<U, K>;
-// assoc(prop, __, obj)(val), when prop is not keyof obj
-export function assoc<U, K extends string>(prop: K, __: Placeholder, obj: U): <T>(val: T) => U & Record<K, T>;
-// assoc(prop, val, obj) when prop is keyof obj and val is same type
-export function assoc<K extends keyof U, U>(prop: K, val: U[K], obj: U): U;
-// assoc(prop, val, obj) when prop is keyof obj  and val is not same type
-export function assoc<T, K extends keyof U, U>(prop: K, val: T, obj: U): Record<K, T> & Omit<U, K>;
-// assoc(prop, val, obj) when prop is not keyof obj
-export function assoc<T, U, K extends string>(prop: K, val: T, obj: U): U & Record<K, T>;
+// assoc(__, val, obj)(prop)
+export function assoc<T, U>(__: Placeholder, val: T, obj: U): <K extends PropertyKey>(prop: K) => K extends keyof U ? T extends U[K] ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
+
+// assoc(prop, __, obj)(val)
+export function assoc<U, K extends PropertyKey>(prop: K, __: Placeholder, obj: U): <T>(val: T) => K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;
+
+// assoc(prop, val, obj)
+export function assoc<T, U, K extends PropertyKey>(prop: K, val: T, obj: U): K extends keyof U ? U[K] extends T ? U : Record<K, T> & Omit<U, K> : U & Record<K, T>;