[yonl]

So we create instance of DataModel once and then we perform operation like filtering, projection of columns, sorting etc. Everytime an operation is performed a new instance of DataModel is returned. Hence its immutable. But under the hood there is only one copy of data resides in the system shared by all instance of DataModel, for every operation we just record a formula and save it on DataModel instance. The data for that particular instance is computed on demand based on the formula. Its not a pure immutability by definition. Hence pseudo-immutable.

However, every operation does not support formula storing. Operation like joining, grouping creates new data.

We are updating the docs rapidly. All this info would be on the docs soon.