3 ms·

Immutability is not the fact that something can not change in this case. It has more to do with the identity of a value. Every time you change anything inside t

by hjntmp 6y ago

Immutability is not the fact that something can not change in this case. It has more to do with the identity of a value. Every time you change anything inside the data structure you get a new reference, that is it!

hjntmp 6y ago
Think of it as versioning for your data. So instead of referring to some data structure by its general concept with immutable data structures we are a lot more specific with respect to the identity represented by the name, here the name represents a version. This is useful because, for example, you stop having the "unmanaged references" you were talking about because now since you are pointing to a version of the data and not the data itself you can be sure of what you are talking about.
- hjntmp 6y ago
  Also remember here the promise is that the data you are talking about wont suddenly change underneath not that the reference 'is up to date". It is not a solution for change in time it is a solution for taking change in time out of the equation when we don't need to talk about that. With immutable ds when we talk about data we are just talking about exactly that and time is taken out of the picture. Its called immutable because now you are talking about facts and not the representation in time of those facts. Because now we are talking in versions so it does not make sense. The thing is this data is a snapshot so you are not guaranteed to have the most up to date snapshot. And that's ok because precisely here we take change in time out of the question in order to be able to talk more precisely about the data. Tracking change in time is another story. So for example you could have things like react. There you have snapshots of the world updating. When you talk about the data it is immutable but then you change it and update the mutable variable where you are keeping change in time.

by hjntmp 6y ago

hjntmp 6y ago

Think of it as versioning for your data. So instead of referring to some data structure by its general concept with immutable data structures we are a lot more specific with respect to the identity represented by the name, here the name represents a version. This is useful because, for example, you stop having the "unmanaged references" you were talking about because now since you are pointing to a version of the data and not the data itself you can be sure of what you are talking about.

hjntmp 6y ago
Also remember here the promise is that the data you are talking about wont suddenly change underneath not that the reference 'is up to date". It is not a solution for change in time it is a solution for taking change in time out of the equation when we don't need to talk about that. With immutable ds when we talk about data we are just talking about exactly that and time is taken out of the picture. Its called immutable because now you are talking about facts and not the representation in time of those facts. Because now we are talking in versions so it does not make sense. The thing is this data is a snapshot so you are not guaranteed to have the most up to date snapshot. And that's ok because precisely here we take change in time out of the question in order to be able to talk more precisely about the data. Tracking change in time is another story. So for example you could have things like react. There you have snapshots of the world updating. When you talk about the data it is immutable but then you change it and update the mutable variable where you are keeping change in time.