Added missing return types to defaultEqualityCheck & areArgumentsShallowlyEqual

Author: nialldbarber

src/index.ts

@@ -17,15 +17,15 @@ export type {
   ParametricSelector
 } from './types'
 
-export const defaultEqualityCheck: EqualityFn = (a, b) => {
+export const defaultEqualityCheck: EqualityFn = (a, b): boolean => {
   return a === b
 }
 
 function areArgumentsShallowlyEqual(
   equalityCheck: EqualityFn,
   prev: unknown[] | IArguments | null,
   next: unknown[] | IArguments | null
-) {
+): boolean {
   if (prev === null || next === null || prev.length !== next.length) {
     return false
   }