| Name : ghc-validation
| |
| Version : 0.5.4
| Vendor : openSUSE
|
| Release : bp150.1.3
| Date : 2018-07-30 21:25:30
|
| Group : Development/Libraries/Haskell
| Source RPM : ghc-validation-0.5.4-bp150.1.3.src.rpm
|
| Size : 0.32 MB
| |
| Packager : https://bugs_opensuse_org
| |
| Summary : A data-type like Either but with an accumulating Applicative
|
Description :
< < http://i.imgur.com/Ns5hntl.jpg>>
Several data-types like Either but with differing properties and type-class
instances.
Library support is provided for those different representations, include
`lens`-related functions for converting between each and abstracting over their
similarities.
* `AccValidation`
The `AccValidation` data type is isomorphic to `Either`, but has an instance of
`Applicative` that accumulates on the error side. That is to say, if two (or
more) errors are encountered, they are appended using a `Semigroup` operation.
As a consequence of this `Applicative` instance, there is no corresponding
`Bind` or `Monad` instance. `AccValidation` is an example of, \"An applicative
functor that is not a monad.\"
* `Validation`
The `Validation` data type is isomorphic to `Either` and has a `Monad` instance
that does the same as `Either`. The only difference to `Either` is the
constructor names and surrounding library support.
* `ValidationT`
The `ValidationT` data type is the monad transformer for `Validation`.
An instance of `MonadTrans` is provided for `(ValidationT err)`. Due to the
arrangement of the `ValidationT` type constructor, which permits a `MonadTrans
instance, there is no possible `Bifunctor` instance. Consequently, the
`ValidationB` data type provides a `Bifunctor` instance (but not a `MonadTrans`
instance). Library support is provided to exploit the isomorphism to
`ValidationB`.
Note that since `AccValidation` is not a monad, there is also no corresponding
monad transformer for this data type.
* `ValidationB`
The `ValidationB` data type is similar to the monad transformer for
`Validation` (`ValidationT`), however, due to the arrangement of the
`ValidationB` type constructor, which permits a `Bifunctor` instance, there is
no possible `MonadTrans` instance. Consequently, the `ValidationT` data type
provides a `MonadTrans` instance (but not a `Bifunctor` instance).
Library support is provided to exploit the isomorphism to `ValidationT`.
* `Validation\'`
The `Validation\' err a` type-alias is equivalent to `ValidationT err Identity
a` and so is isomorphic to `Either` and others. Libraries are supplied
accordingly.
|
RPM found in directory: /packages/linux-pbone/ftp5.gwdg.de/pub/opensuse/repositories/openSUSE:/Backports:/SLE-15/standard/x86_64 |
