ANNOUNCE: lens-family 2.0.0 anniversary edition!
In celebration of the 10th anniversary of Twan van Laarhoven's seminal blog post ``CPS based functional references''[1], I am releasing version 2.0 of lens-family[2] and lens-family-core[3] packages. This new release continues to explore the design of Van Laarhoven style optics with new support for adapters, grates, grids[4], and prisms. To bring support to these new optics necessarily means moving a little further away from syntactic compatibility with Kmett's lens library. In particular, lens-family's 'under' is unrelated to Kmett's lens library's 'under' combinator. Nonetheless the 'under' combinator plays a crucial role in lens-family as a dual to the 'over' combinator and this naming is hard to resist despite the conflict. This new version comes with some minor incompatibilities with the version 1.2 library that may require user updates. See https://hackage.haskell.org/package/lens-family-2.0.0/changelog. [1]https://www.twanvl.nl/blog/haskell/cps-functional-references [2]https://hackage.haskell.org/package/lens-family-2.0.0 [3]https://hackage.haskell.org/package/lens-family-core-2.0.0 [4]A grid is an optic that is both a grate and a traversal. -- Russell O'Connor http://r6.ca/
* '_Left' and '_Right' have been renamed as 'lft_' and 'rgt_'.
Why? I fail to see the benefit of such a breaking change.
On Fri, Jul 19, 2019 at 3:53 PM
In celebration of the 10th anniversary of Twan van Laarhoven's seminal blog post ``CPS based functional references''[1], I am releasing version 2.0 of lens-family[2] and lens-family-core[3] packages. This new release continues to explore the design of Van Laarhoven style optics with new support for adapters, grates, grids[4], and prisms.
To bring support to these new optics necessarily means moving a little further away from syntactic compatibility with Kmett's lens library. In particular, lens-family's 'under' is unrelated to Kmett's lens library's 'under' combinator. Nonetheless the 'under' combinator plays a crucial role in lens-family as a dual to the 'over' combinator and this naming is hard to resist despite the conflict.
This new version comes with some minor incompatibilities with the version 1.2 library that may require user updates. See https://hackage.haskell.org/package/lens-family-2.0.0/changelog.
[1]https://www.twanvl.nl/blog/haskell/cps-functional-references [2]https://hackage.haskell.org/package/lens-family-2.0.0 [3]https://hackage.haskell.org/package/lens-family-core-2.0.0 [4]A grid is an optic that is both a grate and a traversal.
-- Russell O'Connor http://r6.ca/ _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.
On Fri, 19 Jul 2019, Oliver Charles wrote:
* '_Left' and '_Right' have been renamed as 'lft_' and 'rgt_'.
Why? I fail to see the benefit of such a breaking change.
I have a new convention that 'foo_' is defined as 'under foo' (or something similar). Naturally, users can stick with the 1.2 release of lens-family if it suits their needs. -- Russell O'Connor http://r6.ca/ ``My friends, love is better than anger. Hope is better than fear. Optimism is better than dispair. So let us be loving, hopeful and optimistic. And we'll change the world.'' -- Jack Layton
Hey Russell, is there any expository or tech reporty exposition of the
differences in formulation and the why's wherefores of the new major
release? (i'm genuinely curious since i'm quite wimpy in the lens foo)
On Fri, Jul 19, 2019 at 10:53 AM
In celebration of the 10th anniversary of Twan van Laarhoven's seminal blog post ``CPS based functional references''[1], I am releasing version 2.0 of lens-family[2] and lens-family-core[3] packages. This new release continues to explore the design of Van Laarhoven style optics with new support for adapters, grates, grids[4], and prisms.
To bring support to these new optics necessarily means moving a little further away from syntactic compatibility with Kmett's lens library. In particular, lens-family's 'under' is unrelated to Kmett's lens library's 'under' combinator. Nonetheless the 'under' combinator plays a crucial role in lens-family as a dual to the 'over' combinator and this naming is hard to resist despite the conflict.
This new version comes with some minor incompatibilities with the version 1.2 library that may require user updates. See https://hackage.haskell.org/package/lens-family-2.0.0/changelog.
[1]https://www.twanvl.nl/blog/haskell/cps-functional-references [2]https://hackage.haskell.org/package/lens-family-2.0.0 [3]https://hackage.haskell.org/package/lens-family-core-2.0.0 [4]A grid is an optic that is both a grate and a traversal.
-- Russell O'Connor http://r6.ca/ _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.
On Fri, 19 Jul 2019, Carter Schonwald wrote:
Hey Russell, is there any expository or tech reporty exposition of the differences in formulation and the why's wherefores of the new major release? (i'm genuinely curious since i'm quite wimpy in the lens foo)
There hasn't been a change in formulation of used in lens-family, rather the grate-like and adapter-like new formulations have been added along side. Perhaps you are asking about the different formulations between different lens libraries? I'm not sure what the best expositions are. "Profunctor Optics: Modular Data Accessors" by Pickering, Gibbons, and Wu at https://www.cs.ox.ac.uk/people/jeremy.gibbons/publications/poptics.pdf seems like a reasonably good presentation of the implementations. A library user is somewhat insualted from the details of the different implementations through the library combinators, but some differences remain. For example, in lens-family's van Laarhoven implementation, I require explicit casting between Grate-like, Adatper-like, and Lens-like optics, whereas a profunctor based implementation would treat all three class of optics uniformly. That said, you could have a van Laarhoven implementaion that uses Adapter-like for all optics and keep Identity functor wrappers around. This isn't done in lens-family in order to keep backwards compatibility with the original Lens-like optics. I've put out a new relase because I've started using grid optics in my own work. For example, I use 'bend' to create bit-wise parsing of 256-bit hash values @ https://github.com/ElementsProject/simplicity/blob/d1f8298b2ea557073e2358ac0..., and I use an 'fe' grid @ https://github.com/ElementsProject/simplicity/blob/67c838a7b31e7fc555a027950..., etc. to create instances of Arbitrary @ https://github.com/ElementsProject/simplicity/blob/67c838a7b31e7fc555a027950... As far as I know, Kmett's lens library doesn't yet have much support for grates and grids, but I'm sure that will change. That said, a good tutorial on how to program with these new grates and grid optics would be useful. Unfortunately, I think these will take time to be developed. -- Russell O'Connor http://r6.ca/ ``My friends, love is better than anger. Hope is better than fear. Optimism is better than dispair. So let us be loving, hopeful and optimistic. And we'll change the world.'' -- Jack Layton
participants (3)
-
Carter Schonwald -
Oliver Charles -
roconnor＠theorem.ca