[Haskell-cafe] ANNOUNCE: lens-family 2.0.0 anniversary edition!

roconnor at theorem.ca roconnor at theorem.ca
Fri Jul 19 14:52:58 UTC 2019

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>.

[4]A grid is an optic that is both a grate and a traversal.

Russell O'Connor                                      <http://r6.ca/>

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