idris2-lens/README.md

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2023-03-31 13:22:03 -04:00
# Profunctor Optics in Idris2
2023-04-20 14:01:56 -04:00
This package provides utilities for working with lenses, prisms, traversals,
and other optics in Idris. This library uses *profunctor optics*.
Eventually, this library will also include elaboration scripts to automatically
generate lenses for a particular datatype.
## Comparisons
This library is inspired by the Haskell libraries [lens](https://hackage.haskell.org/package/lens-5.2.2),
[optics](https://hackage.haskell.org/package/optics) and [fresnel](https://hackage.haskell.org/package/fresnel),
along with the Purescript library [purescript-profunctor-lenses](https://pursuit.purescript.org/packages/purescript-profunctor-lenses/8.0.0).
Different design decisions are taken from each library.
Like `lens`, this library comes "batteries-included" with many useful lenses for
common types. It also includes the many lens operators. Like `optics`, `fresnel`
and `purescript-profunctor-lenses`, but unlike `lens`, this library uses
profunctor optics as opposed to van Laarhoven optics.
Like `lens` and `fresnel`, this library defines optics through type synonyms and
uses the `(.)` operator to compose them. Like `fresnel`, and unlike `lens`,
this library goes to some effort to ensure that type signatures and error
messages are understandable to some degree.
This library's optics hierarchy is most similar to that of `fresnel`, though it
also includes the `Equality` optic from `lens`. Unlike `fresnel`, this library also
supports indexed optics.
## Installation
This package depends on the `profunctors` package. It can be installed from `pack`
or from its GitHub repository [here](https://github.com/kiana-S/idris2-profunctors).
To install using `idris2` directly:
``` sh
git clone https://github.com/kiana-S/idris2-lens
cd idris2-lens
idris2 --install lens.ipkg
```
Or you can install using [pack](https://github.com/stefan-hoeck/idris2-pack):
``` sh
pack install lens
```