Lazy transformations

[luucvanderzee]

Might be a premature optimization, but it would be cool to make our transformation lazy, like Lazy.js. Could be combined with #30.

[luucvanderzee]

https://medium.com/javascript-scene/transducers-efficient-data-processing-pipelines-in-javascript-7985330fe73d
This approach also looks promising! We would have to implement it for column-oriented data though (have to still wrap my mind around it)