A lens is an object that has both read and write access to a property of an object (or to a path into a tree of nested objects). Rather than passing parts of t

A lens is an object that has both read and write access to a property of an object (or to a path into a tree of nested objects). Rather than passing parts of the model to the children (as you'd do with React props), you pass lenses into said parts. It enables child components to read/write to the global store without knowing its structure. As long as it receives an appropriate (set of) lens(es) it is happy. So, for example, if you have a list of strings, rather than passing the nth string to the nth component, you'd pass a lens to the nth string. The component can then not only read but also write to its slot. Lenses can also be composed, so you can create them on the go as you'd pass sub-props to grand-children. https://github.com/calmm-js/partial.lenses https://github.com/calmm-js/partial.lenses <= a comprehensive lens library http://ramdajs.com/ http://ramdajs.com/ also has lenses. These libs are strongly influenced by the FP world. The underlying data structures are immutable, writing to a lens creates a new version of the store (as efficiently as possible, by recycling intact objects).