The lens-simple package
This module, Lens.Simple,
just re-exports the main modules from Russell O'Connor's
lens-family package, the
original van Laarhoven-O'Connor lens library.
lens-family is particularly remarkable for its minute number of dependencies:
(apart from mtl
they are all ghc 'boot' libraries); but more importantly for its
extreme conceptual simplicity and theoretical soundness. Much of
the material it contains is well-explained, from a tutorial point of view, by
lens-tutorial It is independent,
self-standing and readily intelligible apart from any darker
more general system of combinators that might attempt to extend it. Much
of it ought to be in the Prelude.
Convenient import of the elementary combinators from
however, a little complicated. The idea of this trivial module, then, is just to make a sort of
lens-family equivalent of
the 800 lb gorilla of lens library imports:
namely, the light-weight and elegant:
Check it out, it's even one character shorter!
As another illustration of the simplicity of the
fundamental van Laarhoven-O'Connor lens combinators - and their homogeneity with
Control.Lens - note that the gloss
lens library examples directory - which continues to be
among the best introductory lens tutorials precisely by saying nothing -
requires only this abbreviating change of imports.
If you make that program more complicated,
you might of course end up needing
the more sophisticated material in
its immense mass of dependencies. On the other hand,
you might just need some of the additional material
present in the similarly demystifying
or microlens-th and
the associated modules.
This module was originally intended to simplify the use of packages that
follow the original promise of the van Laarhoven-O'Connor lenses.
Correct practice is to export lenses without depending on a lens-library, where possible.
In basic cases these just use familiar
Prelude types, after all.
Examples of best practices in this respect are e.g. lens-family-th which
doesn't depend on
lens-family despite its name and pipes-related packages like
Lens.Simple also re-exports convenient TH incantations like
makeLenses from Dan Burton's associated
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|Versions||0.1.0.0, 0.1.0.1, 0.1.0.2, 0.1.0.3, 0.1.0.4, 0.1.0.5, 0.1.0.6, 0.1.0.7, 0.1.0.8, 0.1.0.9|
|Dependencies||base (==4.*), lens-family (==1.2.*), lens-family-core (==1.2.*), lens-family-th (<0.6), mtl (>=2.1 && <2.3), transformers (>=0.2.0 && <6) [details]|
|Copyright||2012, 2013, 2014 Russell O'Connor; 2015 Michael Thompson|
|Source repo||head: git clone https://github.com/michaelt/lens-simple|
|Uploaded||Thu Jun 23 15:45:49 UTC 2016 by MichaelThompson|
|Distributions||LTSHaskell:0.1.0.9, NixOS:0.1.0.9, Stackage:0.1.0.9, openSUSE:0.1.0.9|
|Downloads||2972 total (77 in the last 30 days)|
|Rating||(no votes yet) [estimated by rule of succession]|
|Status||Docs uploaded by user
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