# profunctor-optics: An optics library compatible with the typeclasses in 'profunctors'.

[ bsd3, data, lenses, library, profunctors ] [ Propose Tags ]

This package provides utilities for creating and manipulating profunctor-based optics. Some highlights:

Full complement of isos, prisms, lenses, grates, traversals (affine, regular, and non-empty), folds (affine, regular, and non-empty), views, and setters. Many of these have categorical duals.

Composable indexed and co-indexed variants of all of the above.

Compact & straight-forward implementation. No inscrutable internal modules, lawless or otherwise ancillary typeclasses, or heavy type-level machinery.

Fully interoperable. All that is required to create optics (standard, idexable, or co-indexable) is the profunctors package, which is heavily used and seems likely to end up in base at some point. Optics compose with (.) from Prelude as is typical. If you want to provide profunctor optics for your own types in your own libraries, you can do so without incurring a dependency on this package. Conversions to & from the Van Laarhoven representations are provided for each optic type.

Well-documented properties and exportable predicates for testing your own optics.