Become a member
to unlock all features

Level Up!

Access all courses & lessons on egghead today and lock-in your price for life.


    Mutable let bindings in Reason


    Immutability comes with lots of benefits. Working with a programming language with first class immutable data structures is a blaze. Nevertheless sometimes it can be useful to have a binding that's mutable. Using references we can achieve this in ReasonML.



    Become a Member to view code

    You must be a Pro Member to view code

    Access all courses and lessons, track your progress, gain confidence and expertise.

    Become a Member
    and unlock code for this lesson
    orLog In




    Instructor: Let bindings are mutable by default. We can make them mutable using a reference to wrap the actual value. Basically, a reference is like a box, and the content inside can change.

    To update the reference, we can use a column followed by an equals sign. We here refer to the name. The content of our foo changed to six.

    In order to retrieve the value of a reference, we can use the carrot character. References, for example, can be used to store the state of the whole game where you are, like this.

    Keep in mind to use this feature sparingly to avoid unexpected behavior. Immutability comes with lots of benefits, and you better not give them up without any good reasons.