@type/ramda: Add type definition for startsWith (#20594)

* added type definition for startsWith in Ramda

* linting

types/ramda/index.d.ts

@@ -10,6 +10,7 @@
 //                 Jordan Quagliatini <https://github.com/1M0reBug>
 //                 Simon Højberg <https://github.com/hojberg>
 //                 Charles-Philippe Clermont <https://github.com/charlespwd>
+//                 Samson Keung <https://github.com/samsonkeung>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.4
 
@@ -1638,8 +1639,10 @@ declare namespace R {
         /**
          * Checks if a list starts with the provided values
          */
-        startsWith(a: any, list: any): boolean;
-        startsWith(a: any): (list: any) => boolean;
+        startsWith(a: string, list: string): boolean;
+        startsWith(a: string): (list: string) => boolean;
+        startsWith<T>(a: T | T[], list: T[]): boolean;
+        startsWith<T>(a: T | T[]): (list: T[]) => boolean;
 
         /**
          * Subtracts two numbers. Equivalent to `a - b` but curried.

types/ramda/ramda-tests.ts

@@ -1883,6 +1883,15 @@ class Rectangle {
     const b: number[][] = R.splitWhen(R.equals(2))([1, 2, 3, 1, 2, 3]);   // => [[1], [2, 3, 1, 2, 3]]
 };
 
+() => {
+    R.startsWith("a", "abc");   // => true
+    R.startsWith("a")("abc");   // => true
+    R.startsWith(1, [1, 2, 3]);   // => true
+    R.startsWith(1)([1, 2, 3]);   // => true
+    R.startsWith([1], [1, 2, 3]);   // => true
+    R.startsWith([1])([1, 2, 3]);   // => true
+};
+
 () => {
     R.add(2, 3);       // =>  5
     R.add(7)(10);      // => 17