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Functional Programming with ReasonML

Function Definition

Explore how to define and implement functions in ReasonML by understanding their structure, including names, arguments, and expressions. Learn to create reusable code with examples like a double function and prepare for advanced function concepts such as scope.

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As we discussed earlier, a function performs a certain task and returns a value. This implies that the function will contain an expression.

The Need for Functions

A function can be used repeatedly, which helps us avoid writing redundant code.

Let’s look at a simple program where we calculate and print the double of an integer:

Reason
let two = 2;
let seven = 7;
let ten = 10;
let doubleOfTwo = two * 2;
Js.log(doubleOfTwo); /* 4 */
let doubleOfSeven = seven * 2;
Js.log(doubleOfSeven); /* 14 */
let doubleOfTen = ten * 2;
Js.log(doubleOfTen); /* 20 */

The code above is redundantly verbose for no reason. The simple steps are:

  1. Calculate the double.
  2. Print its value.

Let’s ...