This is used to create a reference value. When creating a reference value, there is an option to provide a validator function, which will validate the value created.

This function is used to set the value of a reference to a new value irrespective of whatever is the older value.

This function is used to alter the value of a reference type but in a safe manner. This is run in a thread, which cannot be accessed by another process.

Runs the expression (in an implicit do) in a transaction that encompasses expression and any nested calls.

Commute is also used to change the value of a reference type just like alter and ref-set.