Lens.Simple>, just re-exports the main modules from Russell O'Connor's
<http://hackage.haskell.org/package/lens-family lens-family> package, the
original van Laarhoven-O'Connor lens library. 'lens-family' is particularly
remarkable for its minute number of dependencies: (apart from
<http://hackage.haskell.org/package/mtl 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 <http://hackage.haskell.org/package/lens-tutorial
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 'lens-family', however, a
little complicated. The idea of this trivial module, then, is just to make a
sort of low-powered, minimal-dependency, 'lens-family' equivalent of the 800 lb
gorilla of lens library imports:
> import Control.Lens
namely, the light-weight and elegant:
> import Lens.Simple
Check it out, it's even one character shorter!
The material in <http://hackage.haskell.org/package/lens-tutorial
lens-tutorial> will work fine if you make this substitution in the underlying
source> and follow along as prompted.
As another illustration of the simplicity of the fundamental van
Laarhoven-O'Connor lens combinators - and their homogeneity with 'Control.Lens'
If you make that program more complicated, you might of course end up needing
the more sophisticated material in 'Control.Lens' and its immense mass of
dependencies. On the other hand, you might just need some of the additional
material present in the similarly demystifying
<http://hackage.haskell.org/package/microlens microlens> or
<http://hackage.haskell.org/package/microlens-th microlens-th> and the
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.
<http://hackage.haskell.org/package/lens-family-th lens-family-th> which
doesn't depend on 'lens-family' despite its name and pipes-related packages
like <http://hackage.haskell.org/package/pipes-bytestring pipes-bytestring> and
'Lens.Simple' also re-exports convenient TH incantations like 'makeLenses' from
Dan Burton's associated <http://hackage.haskell.org/package/lens-family-th