Add exercice about 'if' (#40)

* ✨ add bonus (about if) in exo1

* ♻️ improve bonus

* 🔥 remove not clear exercice

* ♻️ better bonus explanations

* ♻️ spaces

src/exo1/exo1.ts

@@ -27,6 +27,17 @@ export const divide = (a: number, b: number): number => {
 export const safeDivide: (a: number, b: number) => Option<number> =
   unimplemented;
 
+
+// You probably wrote `safeDivide` using `if` statements and it's perfectly valid!
+// There are ways to not use `if` statements.
+// Keep in mind that extracting small functions out of pipes and using `if` statements in them 
+// is perfectly fine and is sometimes more readable than not using `if`.
+//
+// BONUS: Try now to re-write `safeDivide` without any `if`
+//
+// HINT: Have a look at `fromPredicate` constructor
+
+
 ///////////////////////////////////////////////////////////////////////////////
 //                                  EITHER                                   //
 ///////////////////////////////////////////////////////////////////////////////