| Copyright | (c) 2018-2020 Kowainik |
|---|---|
| License | MPL-2.0 |
| Maintainer | Kowainik <xrom.xkov@gmail.com> |
| Safe Haskell | None |
| Language | Haskell2010 |
Toml.Codec.BiMap
Description
Implementation of Tagged Partial Bidirectional Isomorphism. This
module contains the BiMap type that represents conversion between
two types with the possibility of failure.
See Toml.Codec.BiMap.Conversion for examples of BiMap with
specific types. The BiMap concept is general and is not specific to
TOML, but in this package most usages of BiMap are between TOML
values and Haskell values.
Synopsis
- data BiMap e a b = BiMap {}
- invert :: BiMap e a b -> BiMap e b a
- iso :: (a -> b) -> (b -> a) -> BiMap e a b
- prism :: (field -> object) -> (object -> Either error field) -> BiMap error object field
- type TomlBiMap = BiMap TomlBiMapError
- data TomlBiMapError
- wrongConstructor :: Show a => Text -> a -> Either TomlBiMapError b
- prettyBiMapError :: TomlBiMapError -> Text
- mkAnyValueBiMap :: forall a (tag :: TValue). (forall (t :: TValue). Value t -> Either MatchError a) -> (a -> Value tag) -> TomlBiMap a AnyValue
- tShow :: Show a => a -> Text
BiMap concept
Partial bidirectional isomorphism. BiMap a b contains two function:
a -> Either e b
b -> Either e a
If you think of types as sets then this data type can be illustrated by the following picture:
BiMap also implements Category typeclass. And this instance can be described
clearly by this illustration:
Since: 0.4.0
iso :: (a -> b) -> (b -> a) -> BiMap e a b Source #
Creates BiMap from isomorphism. Can be used in the following way:
newtype Even = Even Integer newtype Odd = Odd Integer succEven :: Even -> Odd succEven (Even n) = Odd (n + 1) predOdd :: Odd -> Even predOdd (Odd n) = Even (n - 1) _EvenOdd ::BiMape Even Odd _EvenOdd =isosuccEven predOdd
Since: 0.4.0
Arguments
| :: (field -> object) | Constructor |
| -> (object -> Either error field) | Match object to either error or field |
| -> BiMap error object field |
Creates BiMap from prism-like pair of functions. This combinator can be
used to create BiMap for custom sum types like this:
data User
= Admin Integer -- id of admin
| Client Text -- name of the client
deriving (Show)
_Admin :: TomlBiMap User Integer
_Admin = Toml.prism Admin $ \case
Admin i -> Right i
other -> Toml.wrongConstructor "Admin" other
_Client :: TomlBiMap User Text
_Client = Toml.prism Client $ \case
Client n -> Right n
other -> Toml.wrongConstructor "Client" other
Since: 0.4.0
TOML BiMap
Type
Error
data TomlBiMapError Source #
Type of errors for TOML BiMap.
Since: 1.0.0
Constructors
| WrongConstructor | Error for cases with wrong constructors. For
example, you're trying to convert |
| WrongValue | Error for cases with wrong values |
Fields
| |
| ArbitraryError | Arbitrary textual error |
Fields
| |
Instances
Arguments
| :: Show a | |
| => Text | Name of the expected constructor |
| -> a | Actual value |
| -> Either TomlBiMapError b |
Helper to construct WrongConstuctor error.
Since: 1.0.0
prettyBiMapError :: TomlBiMapError -> Text Source #
Converts TomlBiMapError into pretty human-readable text.
Since: 1.0.0