Explore ReasonML's growing popularity and its strong-typed syntax for JavaScript. Learn about creating data objects, functions, and data structures through interactive quizzes and exercises.

ReasonML has been skyrocketing in popularity lately, and for good... reason. Very recently developed by Facebook, it provides users a strong-typed, clean, and efficient syntax for JavaScript, which makes it great for web development. 

This course will get you up to speed programming in Reason. You'll start by learning how to create simple data objects and build up to more powerful tools such as functions and data structures. Along the way, interactive quizzes and exercises will help you gain a stronger grasp of the language.

Anyone looking to put themselves on the cutting-edge of web development would be well served to have a look at this course.

Functional Programming with ReasonML

# Inside the Function Body
In Reason, data created inside the body of a function will not exist outside it. Only the value we return is accessible. For example, this code will produce an error:

let a = 10;
let b = 5;

let product = (a, b) => {
  let c = 20;
  a * b * c;
};

/* Accesing c outside the function */
c;

# Redefining a Function
Because of `let` bindings, we can use the same identifier to define different functions. The latest definition will be selected by the compiler.

let foo = (n) => n - 2;
Js.log(foo(10));

let foo = (n) => n + 2;
Js.log(foo(10));

The cool thing to note is that, if we call the `foo()` function within the second definition, the compiler will use the **old definition** to compute a value. This is because the older definition is the only one that's available when the newer definition is being compiled:

In this lesson, we'll explain the behavior of functions and their scopes.

A Brief Introduction

Data Types

Identifiers

Data Structures

Conditional Expressions

Functions

Loops

Variants

Objects

Function Scope

Inside the Function Body

Redefining a Function