| Copyright | (C) 2013-2016 Edward Kmett, 2015-2016 Artyom |
|---|---|
| License | BSD-style (see the file LICENSE) |
| Safe Haskell | Trustworthy |
| Language | Haskell2010 |
Lens.Micro.Extras
Description
Documentation
view :: Getting a s a -> s -> a Source
>>>view _1 (1, 2)1
The reason it's not in Lens.Micro is that view in lens has a more general signature:
view :: MonadReader s m => Getting a s a -> m a
So, you would be able to use this view with functions, but not in various reader monads. For most people this shouldn't be an issue; if it is for you, use view from microlens-mtl.
preview :: Getting (First a) s a -> s -> Maybe a Source
preview is a synonym for (^?):
>>>preview _head [1,2,3]Just 1
The reason it's not in Lens.Micro is that preview in lens has a more general signature:
preview :: MonadReader s m => Getting (First a) s a -> m (Maybe a)
Just like with view, you would be able to use this preview with functions, but not in reader monads; if this is an issue for you, use preview from microlens-mtl.