Our Maybe’s bind function is like the array’s flatMap (this function is also known as chain). We have “lifted” the number into a container, in this case, an array, we have excluded the value if it is undefined/null (by using filter), and that has allowed us to perform safe operations on it. flatMap(( x) => ) ? 'There was no number to reveal' If above code seems a bit weird to you, which I would expect if you have never done functional programming, let’s do something similar using an array and its functions. getOrElse('There was no number to reveal') console.log(result) Let’s see now how to use this Maybe Monad. If the value is not there, it will just return a Maybe wrapping undefined.Ģ- bind: Similar to map, but the function that is applied returns another Maybe, instead of a simple value.ģ- getOrElse: After all is said and done, it allows us to access the contained value or return the supplied default value if what we have at that point is a Maybe(undefined). What do we have here? Let’s see…we have a factory function (Maybe), that takes a value as a parameter, and returns an object with three methods:ġ- map: It takes a function, and if the value exists, applies that function on the value and returns a new value inside the same Maybe container (although a new instance). One way to do this imperatively could be: const number = // getting number from somewhere (DB/network/etc) let newNumber if (number) ) Let’s pretend there is a number we want to apply an operations to, and if that number is undefined/null, we want to avoid an error or unexpected result.

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