Safe Haskell	None
Language	Haskell2010

LawfulConversions

Contents

Typeclasses
Optics
Instance derivation
Testing

Description

Conversions

The main part of the API is two functions: to and from. Both perform a conversion between two types. The main difference between them is in what the first type application parameter specifies. E.g.:

toString = to @String

fromText = from @Text

The types should be self-evident:

> :t to @String
to @String :: IsSome String b => b -> String

> :t from @Text
from @Text :: IsMany Text b => Text -> b

In other words to and from let you explicitly specify either the source or the target type of a conversion when you need to help the type inferencer or the reader.

Examples

combineEncodings :: ShortByteString -> ByteArray -> [Word8] -> ByteString
combineEncodings a b c =
  from @Builder $
    to a <> to b <> to c

renderNameAndHeight :: Text -> Int -> Text
renderNameAndHeight name height =
  from @StrictTextBuilder $
    "Height of " <> from name <> " is " <> from (show height)

Partial conversions

This library also captures the pattern of smart constructors via the IsSome class, which associates a total to conversion with its partial inverse maybeFrom.

This captures the codec relationship between types. E.g.,

Every Int16 can be losslessly converted into Int32, but not every Int32 can be losslessly converted into Int16.
Every Text can be converted into ByteString via UTF-8 encoding, but not every ByteString forms a valid UTF-8 sequence.
Every URL can be uniquely represented as Text, but most Texts are not URLs unfortunately.
UTCTime, JSON, Email, etc.

Examples

Here's an example of implementing the Smart Constructor pattern.

module Percent (Percent) where

import LawfulConversions

newtype Percent = Percent Double

instance IsSome Double Percent where
  to (Percent double) = double
  maybeFrom double =
    if double < 0 || double > 1
      then Nothing
      else Just (Percent double)

You can also expand upon that and provide a default handling of invalid values effectively providing a lossy canonicalizing conversion (Surjection):

instance IsMany Double Percent where
  from double =
    if double < 0
      then Percent 0
      else if double > 1
        then Percent 1
        else Percent double

However declaring an instance of Is would be incorrect, because this conversion is partial. Namely, while every Percent value can be losslessly transformed into Double, not every Double can be losslessly transformed into Percent.

Synopsis

class IsSome a b where
- to :: b -> a
- maybeFrom :: a -> Maybe b
class IsSome a b => IsMany a b where
- from :: a -> b
class (IsMany a b, Is b a) => Is a b
isSomePrism :: (IsSome a b, Choice p, Applicative f) => p b (f b) -> p a (f a)
isManyIso :: (IsMany a b, Profunctor p, Functor f) => p b (f b) -> p a (f a)
isIso :: (Is a b, Profunctor p, Functor f) => p b (f b) -> p a (f a)
newtype ViaIsSome a b = ViaIsSome b
isSomeProperties :: (IsSome a b, Eq a, Eq b, Show a, Show b, Arbitrary b) => Proxy a -> Proxy b -> [(String, Property)]
isManyProperties :: (IsMany a b, Eq a, Eq b, Show a, Show b, Arbitrary b) => Proxy a -> Proxy b -> [(String, Property)]
isProperties :: (Is a b, Eq a, Eq b, Show a, Show b, Arbitrary a, Arbitrary b) => Proxy a -> Proxy b -> [(String, Property)]

Typeclasses

class IsSome a b where Source #

Evidence that all values of type b form a subset of all values of type a.

From Wikipedia:

In mathematics, a set A is a subset of a set B if all elements of A are also elements of B; B is then a superset of A. It is possible for A and B to be equal; if they are unequal, then A is a proper subset of B. The relationship of one set being a subset of another is called inclusion (or sometimes containment). A is a subset of B may also be expressed as B includes (or contains) A or A is included (or contained) in B. A k-subset is a subset with k elements.

Laws

`to` is injective

For every two values of type b that are not equal converting with to produces values that are not equal as well:

\(b1, b2) -> b1 == b2 || to @a b1 /= to @a b2

`maybeFrom` is a partial inverse of `to`

For all values of b converting to a and then attempting to convert back to b always succeeds and produces a value that is equal to the original:

\b -> maybeFrom (to @a b) == Just b

Testing

For testing whether your instances conform to these laws use isSomeProperties.

Minimal complete definition

to

Methods

to :: b -> a Source #

Convert a value of a subset type to a superset type.

maybeFrom :: a -> Maybe b Source #

Partial inverse of to.

default maybeFrom :: IsSome b a => a -> Maybe b Source #

Requires the presence of IsSome in reverse direction.

Instances

Instances details

IsSome ByteArray Builder Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteStringBuilder Methods to :: Builder -> ByteArray Source # maybeFrom :: ByteArray -> Maybe Builder Source #
IsSome ByteArray ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndByteString Methods to :: ByteString -> ByteArray Source # maybeFrom :: ByteArray -> Maybe ByteString Source #
IsSome ByteArray ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteString Methods to :: ByteString -> ByteArray Source # maybeFrom :: ByteArray -> Maybe ByteString Source #
IsSome ByteArray ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndShortByteString Methods to :: ShortByteString -> ByteArray Source # maybeFrom :: ByteArray -> Maybe ShortByteString Source #
IsSome Int16 Word16 Source #
Instance details Defined in LawfulConversions.Relations.Int16AndWord16 Methods to :: Word16 -> Int16 Source # maybeFrom :: Int16 -> Maybe Word16 Source #
IsSome Int32 Word32 Source #
Instance details Defined in LawfulConversions.Relations.Int32AndWord32 Methods to :: Word32 -> Int32 Source # maybeFrom :: Int32 -> Maybe Word32 Source #
IsSome Int64 Word64 Source #
Instance details Defined in LawfulConversions.Relations.Int64AndWord64 Methods to :: Word64 -> Int64 Source # maybeFrom :: Int64 -> Maybe Word64 Source #
IsSome Int8 Word8 Source #
Instance details Defined in LawfulConversions.Relations.Int8AndWord8 Methods to :: Word8 -> Int8 Source # maybeFrom :: Int8 -> Maybe Word8 Source #
IsSome Word16 Int16 Source #
Instance details Defined in LawfulConversions.Relations.Int16AndWord16 Methods to :: Int16 -> Word16 Source # maybeFrom :: Word16 -> Maybe Int16 Source #
IsSome Word32 Int32 Source #
Instance details Defined in LawfulConversions.Relations.Int32AndWord32 Methods to :: Int32 -> Word32 Source # maybeFrom :: Word32 -> Maybe Int32 Source #
IsSome Word64 Int64 Source #
Instance details Defined in LawfulConversions.Relations.Int64AndWord64 Methods to :: Int64 -> Word64 Source # maybeFrom :: Word64 -> Maybe Int64 Source #
IsSome Word8 Int8 Source #
Instance details Defined in LawfulConversions.Relations.Int8AndWord8 Methods to :: Int8 -> Word8 Source # maybeFrom :: Word8 -> Maybe Int8 Source #
IsSome Builder ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteStringBuilder Methods to :: ByteArray -> Builder Source # maybeFrom :: Builder -> Maybe ByteArray Source #
IsSome Builder ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteStringBuilder Methods to :: ByteString -> Builder Source # maybeFrom :: Builder -> Maybe ByteString Source #
IsSome Builder ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyByteStringBuilder Methods to :: ByteString -> Builder Source # maybeFrom :: Builder -> Maybe ByteString Source #
IsSome Builder ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndShortByteString Methods to :: ShortByteString -> Builder Source # maybeFrom :: Builder -> Maybe ShortByteString Source #
IsSome ByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndByteString Methods to :: ByteArray -> ByteString Source # maybeFrom :: ByteString -> Maybe ByteArray Source #
IsSome ByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteStringBuilder Methods to :: Builder -> ByteString Source # maybeFrom :: ByteString -> Maybe Builder Source #
IsSome ByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteString Methods to :: ByteString -> ByteString Source # maybeFrom :: ByteString -> Maybe ByteString Source #
IsSome ByteString ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndShortByteString Methods to :: ShortByteString -> ByteString Source # maybeFrom :: ByteString -> Maybe ShortByteString Source #
IsSome ByteString Text Source #	UTF-8 codec.
Instance details Defined in LawfulConversions.Relations.ByteStringAndText Methods to :: Text -> ByteString Source # maybeFrom :: ByteString -> Maybe Text Source #
IsSome ByteString Text Source #	UTF-8 codec.
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyText Methods to :: Text -> ByteString Source # maybeFrom :: ByteString -> Maybe Text Source #
IsSome ByteString String Source #	UTF-8 codec.
Instance details Defined in LawfulConversions.Relations.ByteStringAndString Methods to :: String -> ByteString Source # maybeFrom :: ByteString -> Maybe String Source #
IsSome ByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteString Methods to :: ByteArray -> ByteString Source # maybeFrom :: ByteString -> Maybe ByteArray Source #
IsSome ByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyByteStringBuilder Methods to :: Builder -> ByteString Source # maybeFrom :: ByteString -> Maybe Builder Source #
IsSome ByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteString Methods to :: ByteString -> ByteString Source # maybeFrom :: ByteString -> Maybe ByteString Source #
IsSome ByteString ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndShortByteString Methods to :: ShortByteString -> ByteString Source # maybeFrom :: ByteString -> Maybe ShortByteString Source #
IsSome ByteString Text Source #	UTF-8 codec.
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndText Methods to :: Text -> ByteString Source # maybeFrom :: ByteString -> Maybe Text Source #
IsSome ByteString Text Source #	UTF-8 codec.
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyText Methods to :: Text -> ByteString Source # maybeFrom :: ByteString -> Maybe Text Source #
IsSome ByteString String Source #	UTF-8 codec.
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndString Methods to :: String -> ByteString Source # maybeFrom :: ByteString -> Maybe String Source #
IsSome ShortByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndShortByteString Methods to :: ByteArray -> ShortByteString Source # maybeFrom :: ShortByteString -> Maybe ByteArray Source #
IsSome ShortByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndShortByteString Methods to :: Builder -> ShortByteString Source # maybeFrom :: ShortByteString -> Maybe Builder Source #
IsSome ShortByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndShortByteString Methods to :: ByteString -> ShortByteString Source # maybeFrom :: ShortByteString -> Maybe ByteString Source #
IsSome ShortByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndShortByteString Methods to :: ByteString -> ShortByteString Source # maybeFrom :: ShortByteString -> Maybe ByteString Source #
IsSome Text Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndText Methods to :: Builder -> Text Source # maybeFrom :: Text -> Maybe Builder Source #
IsSome Text Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndText Methods to :: Text -> Text Source # maybeFrom :: Text -> Maybe Text Source #
IsSome Text StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndText Methods to :: StrictBuilder -> Text Source # maybeFrom :: Text -> Maybe StrictBuilder Source #
IsSome Text Day Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.DayAndText Methods to :: Day -> Text Source # maybeFrom :: Text -> Maybe Day Source #
IsSome Text UTCTime Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.TextAndUtcTime Methods to :: UTCTime -> Text Source # maybeFrom :: Text -> Maybe UTCTime Source #
IsSome Text UUID Source #
Instance details Defined in LawfulConversions.Relations.TextAndUuid Methods to :: UUID -> Text Source # maybeFrom :: Text -> Maybe UUID Source #
IsSome Builder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndText Methods to :: Text -> Builder Source # maybeFrom :: Builder -> Maybe Text Source #
IsSome Builder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndLazyTextBuilder Methods to :: Text -> Builder Source # maybeFrom :: Builder -> Maybe Text Source #
IsSome Builder StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndStrictTextBuilder Methods to :: StrictBuilder -> Builder Source # maybeFrom :: Builder -> Maybe StrictBuilder Source #
IsSome Builder Day Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.DayAndLazyTextBuilder Methods to :: Day -> Builder Source # maybeFrom :: Builder -> Maybe Day Source #
IsSome Builder UTCTime Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndUtcTime Methods to :: UTCTime -> Builder Source # maybeFrom :: Builder -> Maybe UTCTime Source #
IsSome Builder UUID Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndUuid Methods to :: UUID -> Builder Source # maybeFrom :: Builder -> Maybe UUID Source #
IsSome Text Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndText Methods to :: Text -> Text Source # maybeFrom :: Text -> Maybe Text Source #
IsSome Text Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndLazyTextBuilder Methods to :: Builder -> Text Source # maybeFrom :: Text -> Maybe Builder Source #
IsSome Text StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndStrictTextBuilder Methods to :: StrictBuilder -> Text Source # maybeFrom :: Text -> Maybe StrictBuilder Source #
IsSome Text Day Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.DayAndLazyText Methods to :: Day -> Text Source # maybeFrom :: Text -> Maybe Day Source #
IsSome Text UTCTime Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.LazyTextAndUtcTime Methods to :: UTCTime -> Text Source # maybeFrom :: Text -> Maybe UTCTime Source #
IsSome Text UUID Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndUuid Methods to :: UUID -> Text Source # maybeFrom :: Text -> Maybe UUID Source #
IsSome StrictBuilder Text Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndText Methods to :: Text -> StrictBuilder Source # maybeFrom :: StrictBuilder -> Maybe Text Source #
IsSome StrictBuilder Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndStrictTextBuilder Methods to :: Builder -> StrictBuilder Source # maybeFrom :: StrictBuilder -> Maybe Builder Source #
IsSome StrictBuilder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndStrictTextBuilder Methods to :: Text -> StrictBuilder Source # maybeFrom :: StrictBuilder -> Maybe Text Source #
IsSome StrictBuilder Day Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.DayAndStrictTextBuilder Methods to :: Day -> StrictBuilder Source # maybeFrom :: StrictBuilder -> Maybe Day Source #
IsSome StrictBuilder UTCTime Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndUtcTime Methods to :: UTCTime -> StrictBuilder Source # maybeFrom :: StrictBuilder -> Maybe UTCTime Source #
IsSome StrictBuilder UUID Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndUuid Methods to :: UUID -> StrictBuilder Source # maybeFrom :: StrictBuilder -> Maybe UUID Source #
IsSome String Text Source #
Instance details Defined in LawfulConversions.Relations.StringAndText Methods to :: Text -> String Source # maybeFrom :: String -> Maybe Text Source #
IsSome String Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndString Methods to :: Builder -> String Source # maybeFrom :: String -> Maybe Builder Source #
IsSome String Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndString Methods to :: Text -> String Source # maybeFrom :: String -> Maybe Text Source #
IsSome String StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndString Methods to :: StrictBuilder -> String Source # maybeFrom :: String -> Maybe StrictBuilder Source #
IsSome String Day Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.DayAndString Methods to :: Day -> String Source # maybeFrom :: String -> Maybe Day Source #
IsSome String UTCTime Source #	Implements ISO-8601.
Instance details Defined in LawfulConversions.Relations.StringAndUtcTime Methods to :: UTCTime -> String Source # maybeFrom :: String -> Maybe UTCTime Source #
IsSome String UUID Source #
Instance details Defined in LawfulConversions.Relations.StringAndUuid Methods to :: UUID -> String Source # maybeFrom :: String -> Maybe UUID Source #
IsSome Int Word Source #
Instance details Defined in LawfulConversions.Relations.IntAndWord Methods to :: Word -> Int Source # maybeFrom :: Int -> Maybe Word Source #
IsSome Word Int Source #
Instance details Defined in LawfulConversions.Relations.IntAndWord Methods to :: Int -> Word Source # maybeFrom :: Word -> Maybe Int Source #
IsSome a Void Source #	The empty set has no elements, and therefore is vacuously a subset of any set.
Instance details Defined in LawfulConversions.Classes.IsSome Methods to :: Void -> a Source # maybeFrom :: a -> Maybe Void Source #
IsSome a a Source #	Every type is isomorphic to itself.
Instance details Defined in LawfulConversions.Classes.IsSome Methods to :: a -> a Source # maybeFrom :: a -> Maybe a Source #
IsSome ByteArray [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndWord8List Methods to :: [Word8] -> ByteArray Source # maybeFrom :: ByteArray -> Maybe [Word8] Source #
IsSome Builder [Word8] Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndWord8List Methods to :: [Word8] -> Builder Source # maybeFrom :: Builder -> Maybe [Word8] Source #
IsSome ByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndWord8List Methods to :: [Word8] -> ByteString Source # maybeFrom :: ByteString -> Maybe [Word8] Source #
IsSome ByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndWord8List Methods to :: [Word8] -> ByteString Source # maybeFrom :: ByteString -> Maybe [Word8] Source #
IsSome ShortByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ShortByteStringAndWord8List Methods to :: [Word8] -> ShortByteString Source # maybeFrom :: ShortByteString -> Maybe [Word8] Source #
IsSome IntSet (Set Int) Source #
Instance details Defined in LawfulConversions.Relations.IntSetAndSetOfInt Methods to :: Set Int -> IntSet Source # maybeFrom :: IntSet -> Maybe (Set Int) Source #
IsSome a b => IsSome a (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods to :: ViaIsSome a b -> a Source # maybeFrom :: a -> Maybe (ViaIsSome a b) Source #
IsSome b (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods to :: ViaIsSome a b -> b Source # maybeFrom :: b -> Maybe (ViaIsSome a b) Source #
IsSome (Set Int) IntSet Source #
Instance details Defined in LawfulConversions.Relations.IntSetAndSetOfInt Methods to :: IntSet -> Set Int Source # maybeFrom :: Set Int -> Maybe IntSet Source #
IsSome [Word8] ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndWord8List Methods to :: ByteArray -> [Word8] Source # maybeFrom :: [Word8] -> Maybe ByteArray Source #
IsSome [Word8] Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndWord8List Methods to :: Builder -> [Word8] Source # maybeFrom :: [Word8] -> Maybe Builder Source #
IsSome [Word8] ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndWord8List Methods to :: ByteString -> [Word8] Source # maybeFrom :: [Word8] -> Maybe ByteString Source #
IsSome [Word8] ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndWord8List Methods to :: ByteString -> [Word8] Source # maybeFrom :: [Word8] -> Maybe ByteString Source #
IsSome [Word8] ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ShortByteStringAndWord8List Methods to :: ShortByteString -> [Word8] Source # maybeFrom :: [Word8] -> Maybe ShortByteString Source #
IsSome (Seq a) (Vector a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndSeq Methods to :: Vector a -> Seq a Source # maybeFrom :: Seq a -> Maybe (Vector a) Source #
IsSome (Seq a) [a] Source #
Instance details Defined in LawfulConversions.Relations.ListAndSeq Methods to :: [a] -> Seq a Source # maybeFrom :: Seq a -> Maybe [a] Source #
IsSome (Vector a) (Seq a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndSeq Methods to :: Seq a -> Vector a Source # maybeFrom :: Vector a -> Maybe (Seq a) Source #
IsSome (Vector a) [a] Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndList Methods to :: [a] -> Vector a Source # maybeFrom :: Vector a -> Maybe [a] Source #
IsSome [a] (Seq a) Source #
Instance details Defined in LawfulConversions.Relations.ListAndSeq Methods to :: Seq a -> [a] Source # maybeFrom :: [a] -> Maybe (Seq a) Source #
IsSome [a] (Vector a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndList Methods to :: Vector a -> [a] Source # maybeFrom :: [a] -> Maybe (Vector a) Source #
IsSome (IntMap v) (Map Int v) Source #
Instance details Defined in LawfulConversions.Relations.IntMapAndMapOfInt Methods to :: Map Int v -> IntMap v Source # maybeFrom :: IntMap v -> Maybe (Map Int v) Source #
IsSome (ViaIsSome a b) b Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods to :: b -> ViaIsSome a b Source # maybeFrom :: ViaIsSome a b -> Maybe b Source #
IsSome (Map Int v) (IntMap v) Source #
Instance details Defined in LawfulConversions.Relations.IntMapAndMapOfInt Methods to :: IntMap v -> Map Int v Source # maybeFrom :: Map Int v -> Maybe (IntMap v) Source #

class IsSome a b => IsMany a b where Source #

Lossy or canonicalizing conversion. Captures mappings from multiple alternative inputs into one output.

E.g.,

ByteString can be decoded into Text with UTF-8 leniently, replacing the invalid chars with a default char.
String has a wider range of supported chars than Text, so some chars get replaced too.

Laws

`from` is an inverse of `to`

\b -> b == from (to @a b)

Testing

For testing whether your instances conform to these laws use isManyProperties.

Minimal complete definition

Nothing

Methods

from :: a -> b Source #

Possibly lossy inverse of to. Surjection from a to b.

Particularly useful in combination with the TypeApplications extension, where it allows to specify the input type, e.g.:

fromText :: IsMany Text b => Text -> b
fromText = from @Text

The first type application of the to function on the other hand specifies the output data type.

default from :: IsSome b a => a -> b Source #

Requires the presence of IsSome in reverse direction.

Instances

Instances details

IsMany ByteArray Builder Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteStringBuilder Methods from :: ByteArray -> Builder Source #
IsMany ByteArray ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndByteString Methods from :: ByteArray -> ByteString Source #
IsMany ByteArray ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteString Methods from :: ByteArray -> ByteString Source #
IsMany ByteArray ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndShortByteString Methods from :: ByteArray -> ShortByteString Source #
IsMany Int16 Word16 Source #
Instance details Defined in LawfulConversions.Relations.Int16AndWord16 Methods from :: Int16 -> Word16 Source #
IsMany Int32 Word32 Source #
Instance details Defined in LawfulConversions.Relations.Int32AndWord32 Methods from :: Int32 -> Word32 Source #
IsMany Int64 Word64 Source #
Instance details Defined in LawfulConversions.Relations.Int64AndWord64 Methods from :: Int64 -> Word64 Source #
IsMany Int8 Word8 Source #
Instance details Defined in LawfulConversions.Relations.Int8AndWord8 Methods from :: Int8 -> Word8 Source #
IsMany Word16 Int16 Source #
Instance details Defined in LawfulConversions.Relations.Int16AndWord16 Methods from :: Word16 -> Int16 Source #
IsMany Word32 Int32 Source #
Instance details Defined in LawfulConversions.Relations.Int32AndWord32 Methods from :: Word32 -> Int32 Source #
IsMany Word64 Int64 Source #
Instance details Defined in LawfulConversions.Relations.Int64AndWord64 Methods from :: Word64 -> Int64 Source #
IsMany Word8 Int8 Source #
Instance details Defined in LawfulConversions.Relations.Int8AndWord8 Methods from :: Word8 -> Int8 Source #
IsMany Builder ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteStringBuilder Methods from :: Builder -> ByteArray Source #
IsMany Builder ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteStringBuilder Methods from :: Builder -> ByteString Source #
IsMany Builder ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyByteStringBuilder Methods from :: Builder -> ByteString Source #
IsMany Builder ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndShortByteString Methods from :: Builder -> ShortByteString Source #
IsMany ByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndByteString Methods from :: ByteString -> ByteArray Source #
IsMany ByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteStringBuilder Methods from :: ByteString -> Builder Source #
IsMany ByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteString Methods from :: ByteString -> ByteString Source #
IsMany ByteString ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndShortByteString Methods from :: ByteString -> ShortByteString Source #
IsMany ByteString Text Source #	Lenient UTF-8 decoding.
Instance details Defined in LawfulConversions.Relations.ByteStringAndText Methods from :: ByteString -> Text Source #
IsMany ByteString Text Source #	Lenient UTF-8 decoding.
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyText Methods from :: ByteString -> Text Source #
IsMany ByteString String Source #	Lenient UTF-8 decoding.
Instance details Defined in LawfulConversions.Relations.ByteStringAndString Methods from :: ByteString -> String Source #
IsMany ByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteString Methods from :: ByteString -> ByteArray Source #
IsMany ByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyByteStringBuilder Methods from :: ByteString -> Builder Source #
IsMany ByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteString Methods from :: ByteString -> ByteString Source #
IsMany ByteString ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndShortByteString Methods from :: ByteString -> ShortByteString Source #
IsMany ByteString Text Source #	Lenient UTF-8 decoding.
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndText Methods from :: ByteString -> Text Source #
IsMany ByteString Text Source #	Lenient UTF-8 decoding.
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyText Methods from :: ByteString -> Text Source #
IsMany ByteString String Source #	Lenient UTF-8 decoding.
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndString Methods from :: ByteString -> String Source #
IsMany ShortByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndShortByteString Methods from :: ShortByteString -> ByteArray Source #
IsMany ShortByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndShortByteString Methods from :: ShortByteString -> Builder Source #
IsMany ShortByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndShortByteString Methods from :: ShortByteString -> ByteString Source #
IsMany ShortByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndShortByteString Methods from :: ShortByteString -> ByteString Source #
IsMany Text Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndText Methods from :: Text -> Builder Source #
IsMany Text Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndText Methods from :: Text -> Text Source #
IsMany Text StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndText Methods from :: Text -> StrictBuilder Source #
IsMany Builder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndText Methods from :: Builder -> Text Source #
IsMany Builder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndLazyTextBuilder Methods from :: Builder -> Text Source #
IsMany Builder StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndStrictTextBuilder Methods from :: Builder -> StrictBuilder Source #
IsMany Text Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndText Methods from :: Text -> Text Source #
IsMany Text Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndLazyTextBuilder Methods from :: Text -> Builder Source #
IsMany Text StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndStrictTextBuilder Methods from :: Text -> StrictBuilder Source #
IsMany StrictBuilder Text Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndText Methods from :: StrictBuilder -> Text Source #
IsMany StrictBuilder Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndStrictTextBuilder Methods from :: StrictBuilder -> Builder Source #
IsMany StrictBuilder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndStrictTextBuilder Methods from :: StrictBuilder -> Text Source #
IsMany String Text Source #
Instance details Defined in LawfulConversions.Relations.StringAndText Methods from :: String -> Text Source #
IsMany String Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndString Methods from :: String -> Builder Source #
IsMany String Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndString Methods from :: String -> Text Source #
IsMany String StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndString Methods from :: String -> StrictBuilder Source #
IsMany Int Word Source #
Instance details Defined in LawfulConversions.Relations.IntAndWord Methods from :: Int -> Word Source #
IsMany Word Int Source #
Instance details Defined in LawfulConversions.Relations.IntAndWord Methods from :: Word -> Int Source #
IsMany a a Source #
Instance details Defined in LawfulConversions.Classes.IsMany Methods from :: a -> a Source #
IsMany ByteArray [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndWord8List Methods from :: ByteArray -> [Word8] Source #
IsMany Builder [Word8] Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndWord8List Methods from :: Builder -> [Word8] Source #
IsMany ByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndWord8List Methods from :: ByteString -> [Word8] Source #
IsMany ByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndWord8List Methods from :: ByteString -> [Word8] Source #
IsMany ShortByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ShortByteStringAndWord8List Methods from :: ShortByteString -> [Word8] Source #
IsMany IntSet (Set Int) Source #
Instance details Defined in LawfulConversions.Relations.IntSetAndSetOfInt Methods from :: IntSet -> Set Int Source #
IsMany b (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods from :: b -> ViaIsSome a b Source #
IsMany (Set Int) IntSet Source #
Instance details Defined in LawfulConversions.Relations.IntSetAndSetOfInt Methods from :: Set Int -> IntSet Source #
IsMany [Word8] ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndWord8List Methods from :: [Word8] -> ByteArray Source #
IsMany [Word8] Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndWord8List Methods from :: [Word8] -> Builder Source #
IsMany [Word8] ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndWord8List Methods from :: [Word8] -> ByteString Source #
IsMany [Word8] ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndWord8List Methods from :: [Word8] -> ByteString Source #
IsMany [Word8] ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ShortByteStringAndWord8List Methods from :: [Word8] -> ShortByteString Source #
IsMany (Seq a) (Vector a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndSeq Methods from :: Seq a -> Vector a Source #
IsMany (Seq a) [a] Source #
Instance details Defined in LawfulConversions.Relations.ListAndSeq Methods from :: Seq a -> [a] Source #
IsMany (Vector a) (Seq a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndSeq Methods from :: Vector a -> Seq a Source #
IsMany (Vector a) [a] Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndList Methods from :: Vector a -> [a] Source #
IsMany [a] (Seq a) Source #
Instance details Defined in LawfulConversions.Relations.ListAndSeq Methods from :: [a] -> Seq a Source #
IsMany [a] (Vector a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndList Methods from :: [a] -> Vector a Source #
IsMany (IntMap v) (Map Int v) Source #
Instance details Defined in LawfulConversions.Relations.IntMapAndMapOfInt Methods from :: IntMap v -> Map Int v Source #
IsMany (ViaIsSome a b) b Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods from :: ViaIsSome a b -> b Source #
IsMany (Map Int v) (IntMap v) Source #
Instance details Defined in LawfulConversions.Relations.IntMapAndMapOfInt Methods from :: Map Int v -> IntMap v Source #

class (IsMany a b, Is b a) => Is a b Source #

Bidirectional conversion between two types with no loss of information.

The bidirectionality is encoded via a recursive dependency with arguments flipped.

You can read the signature Is a b as "B is A".

Laws

`from` is an inverse of `to`

For all values of b converting from b to a and then converting from a to b produces the original value:

\b -> b == from (to @a b)

`to` is an inverse of `from`

For all values of a converting from a to b and then converting from b to a produces the original value:

\a -> a == to (from @a @b a)

Testing

For testing whether your instances conform to these laws use isProperties.

Instance Definition

For each pair of isomorphic types (A and B) the compiler will require you to define six instances, namely: Is A B and Is B A, IsMany A B and IsMany B A, IsSome A B and IsSome B A.

Instances of Is do not define any functions and serve merely as a statement that the laws are satisfied.

Example: Lazy Text and Text

instance IsSome Data.Text.Lazy.LazyText Data.Text.Text where
  to = LazyText.fromStrict

instance IsSome Data.Text.Text Data.Text.Lazy.LazyText where
  to = LazyText.toStrict

instance IsMany Data.Text.Lazy.LazyText Data.Text.Text

instance IsMany Data.Text.Text Data.Text.Lazy.LazyText

instance Is Data.Text.Lazy.LazyText Data.Text.Text

instance Is Data.Text.Text Data.Text.Lazy.LazyText

Instances

Instances details

Is ByteArray Builder Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteStringBuilder
Is ByteArray ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndByteString
Is ByteArray ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteString
Is ByteArray ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndShortByteString
Is Int16 Word16 Source #
Instance details Defined in LawfulConversions.Relations.Int16AndWord16
Is Int32 Word32 Source #
Instance details Defined in LawfulConversions.Relations.Int32AndWord32
Is Int64 Word64 Source #
Instance details Defined in LawfulConversions.Relations.Int64AndWord64
Is Int8 Word8 Source #
Instance details Defined in LawfulConversions.Relations.Int8AndWord8
Is Word16 Int16 Source #
Instance details Defined in LawfulConversions.Relations.Int16AndWord16
Is Word32 Int32 Source #
Instance details Defined in LawfulConversions.Relations.Int32AndWord32
Is Word64 Int64 Source #
Instance details Defined in LawfulConversions.Relations.Int64AndWord64
Is Word8 Int8 Source #
Instance details Defined in LawfulConversions.Relations.Int8AndWord8
Is Builder ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteStringBuilder
Is Builder ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteStringBuilder
Is Builder ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyByteStringBuilder
Is Builder ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndShortByteString
Is ByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndByteString
Is ByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteStringBuilder
Is ByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteString
Is ByteString ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndShortByteString
Is ByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndLazyByteString
Is ByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndLazyByteStringBuilder
Is ByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndLazyByteString
Is ByteString ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndShortByteString
Is ShortByteString ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndShortByteString
Is ShortByteString Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndShortByteString
Is ShortByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndShortByteString
Is ShortByteString ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndShortByteString
Is Text Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndText
Is Text Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndText
Is Text StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndText
Is Builder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndText
Is Builder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndLazyTextBuilder
Is Builder StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndStrictTextBuilder
Is Text Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndText
Is Text Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndLazyTextBuilder
Is Text StrictBuilder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndStrictTextBuilder
Is StrictBuilder Text Source #
Instance details Defined in LawfulConversions.Relations.StrictTextBuilderAndText
Is StrictBuilder Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyTextBuilderAndStrictTextBuilder
Is StrictBuilder Text Source #
Instance details Defined in LawfulConversions.Relations.LazyTextAndStrictTextBuilder
Is Int Word Source #
Instance details Defined in LawfulConversions.Relations.IntAndWord
Is Word Int Source #
Instance details Defined in LawfulConversions.Relations.IntAndWord
Is a a Source #	Any type is isomorphic to itself.
Instance details Defined in LawfulConversions.Classes.Is
Is ByteArray [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndWord8List
Is Builder [Word8] Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndWord8List
Is ByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndWord8List
Is ByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndWord8List
Is ShortByteString [Word8] Source #
Instance details Defined in LawfulConversions.Relations.ShortByteStringAndWord8List
Is IntSet (Set Int) Source #
Instance details Defined in LawfulConversions.Relations.IntSetAndSetOfInt
Is b (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome
Is (Set Int) IntSet Source #
Instance details Defined in LawfulConversions.Relations.IntSetAndSetOfInt
Is [Word8] ByteArray Source #
Instance details Defined in LawfulConversions.Relations.ByteArrayAndWord8List
Is [Word8] Builder Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringBuilderAndWord8List
Is [Word8] ByteString Source #
Instance details Defined in LawfulConversions.Relations.ByteStringAndWord8List
Is [Word8] ByteString Source #
Instance details Defined in LawfulConversions.Relations.LazyByteStringAndWord8List
Is [Word8] ShortByteString Source #
Instance details Defined in LawfulConversions.Relations.ShortByteStringAndWord8List
Is (Seq a) (Vector a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndSeq
Is (Seq a) [a] Source #
Instance details Defined in LawfulConversions.Relations.ListAndSeq
Is (Vector a) (Seq a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndSeq
Is (Vector a) [a] Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndList
Is [a] (Seq a) Source #
Instance details Defined in LawfulConversions.Relations.ListAndSeq
Is [a] (Vector a) Source #
Instance details Defined in LawfulConversions.Relations.BoxedVectorAndList
Is (IntMap v) (Map Int v) Source #
Instance details Defined in LawfulConversions.Relations.IntMapAndMapOfInt
Is (ViaIsSome a b) b Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome
Is (Map Int v) (IntMap v) Source #
Instance details Defined in LawfulConversions.Relations.IntMapAndMapOfInt

Optics

isSomePrism :: (IsSome a b, Choice p, Applicative f) => p b (f b) -> p a (f a) Source #

Van-Laarhoven-style Prism, compatible with libraries like "lens" and "optics".

isManyIso :: (IsMany a b, Profunctor p, Functor f) => p b (f b) -> p a (f a) Source #

Van-Laarhoven-style Isomorphism, compatible with libraries like "lens" and "optics".

isIso :: (Is a b, Profunctor p, Functor f) => p b (f b) -> p a (f a) Source #

Van-Laarhoven-style Isomorphism, compatible with libraries like "lens" and "optics".

Instance derivation

Proxy data-types useful for deriving various standard instances using the DerivingVia extension.

newtype ViaIsSome a b Source #

Helper for deriving common instances on types which have an instance of IsSome a using the DerivingVia extension.

E.g.,

newtype Percent = Percent Double
  deriving newtype (Show, Eq, Ord)
  deriving (Read, Arbitrary) via (ViaIsSome Double Percent)

instance IsSome Double Percent where
  to (Percent double) = double
  maybeFrom double =
    if double < 0 || double > 1
      then Nothing
      else Just (Percent double)

In the code above all the instances that are able to construct the values of Percent are automatically derived based on the IsSome Double Percent instance. This guarantees that they only construct values that pass thru the checks defined in maybeFrom.

Constructors

ViaIsSome b

Instances

Instances details

Is b (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome
IsMany b (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods from :: b -> ViaIsSome a b Source #
IsSome a b => IsSome a (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods to :: ViaIsSome a b -> a Source # maybeFrom :: a -> Maybe (ViaIsSome a b) Source #
IsSome b (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods to :: ViaIsSome a b -> b Source # maybeFrom :: b -> Maybe (ViaIsSome a b) Source #
(IsSome a b, Arbitrary a) => Arbitrary (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods arbitrary :: Gen (ViaIsSome a b) shrink :: ViaIsSome a b -> [ViaIsSome a b]
(IsSome a b, IsString a) => IsString (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods fromString :: String -> ViaIsSome a b
(IsSome a b, Read a) => Read (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods readsPrec :: Int -> ReadS (ViaIsSome a b) readList :: ReadS [ViaIsSome a b] readPrec :: ReadPrec (ViaIsSome a b) readListPrec :: ReadPrec [ViaIsSome a b]
(IsSome a b, Show a) => Show (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods showsPrec :: Int -> ViaIsSome a b -> ShowS show :: ViaIsSome a b -> String showList :: [ViaIsSome a b] -> ShowS
(IsSome a b, Eq a) => Eq (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods (==) :: ViaIsSome a b -> ViaIsSome a b -> Bool (/=) :: ViaIsSome a b -> ViaIsSome a b -> Bool
(IsSome a b, Ord a) => Ord (ViaIsSome a b) Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods compare :: ViaIsSome a b -> ViaIsSome a b -> Ordering (<) :: ViaIsSome a b -> ViaIsSome a b -> Bool (<=) :: ViaIsSome a b -> ViaIsSome a b -> Bool (>) :: ViaIsSome a b -> ViaIsSome a b -> Bool (>=) :: ViaIsSome a b -> ViaIsSome a b -> Bool max :: ViaIsSome a b -> ViaIsSome a b -> ViaIsSome a b min :: ViaIsSome a b -> ViaIsSome a b -> ViaIsSome a b
Is (ViaIsSome a b) b Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome
IsMany (ViaIsSome a b) b Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods from :: ViaIsSome a b -> b Source #
IsSome (ViaIsSome a b) b Source #
Instance details Defined in LawfulConversions.Proxies.ViaIsSome Methods to :: b -> ViaIsSome a b Source # maybeFrom :: ViaIsSome a b -> Maybe b Source #

Testing

isSomeProperties :: (IsSome a b, Eq a, Eq b, Show a, Show b, Arbitrary b) => Proxy a -> Proxy b -> [(String, Property)] Source #

Properties testing whether an instance satisfies the laws of IsSome.

The instance is identified via the proxy types that you provide.

E.g., here's how you can integrate it into an Hspec test-suite:

spec = do
  describe "IsSome laws" do
    traverse_
      (uncurry prop)
      (isSomeProperties @Int32 @Int16 Proxy Proxy)

isManyProperties :: (IsMany a b, Eq a, Eq b, Show a, Show b, Arbitrary b) => Proxy a -> Proxy b -> [(String, Property)] Source #

Properties testing whether an instance satisfies the laws of IsMany.

The instance is identified via the proxy types that you provide.

E.g., here's how you can integrate it into an Hspec test-suite:

spec = do
  describe "IsMany laws" do
    traverse_
      (uncurry prop)
      (isManyProperties @String @Text Proxy Proxy)

isProperties :: (Is a b, Eq a, Eq b, Show a, Show b, Arbitrary a, Arbitrary b) => Proxy a -> Proxy b -> [(String, Property)] Source #

Properties testing whether an instance satisfies the laws of Is.

The instance is identified via the proxy types that you provide.

E.g., here's how you can integrate it into an Hspec test-suite:

spec = do
  describe "Is laws" do
    traverse_
      (uncurry prop)
      (isProperties @Int32 @Word32 Proxy Proxy)

Conversions

Examples

Partial conversions

Examples

Typeclasses

Laws

to is injective

maybeFrom is a partial inverse of to

Testing

Instances

Laws

from is an inverse of to

Testing

Instances

Laws

from is an inverse of to

to is an inverse of from

Testing

Instance Definition

Example: Lazy Text and Text

Instances

Optics

Instance derivation

Instances

Testing

`to` is injective

`maybeFrom` is a partial inverse of `to`

`from` is an inverse of `to`

`from` is an inverse of `to`

`to` is an inverse of `from`