| Safe Haskell | Safe-Inferred |
|---|---|
| Language | GHC2021 |
Strongweak.Strengthen
Synopsis
- class Weaken a => Strengthen a where
- strengthen :: Weak a -> Result a
- restrengthen :: (Strengthen a, Weaken a) => a -> Result a
- type Result = Validation StrengthenFailure
- strengthenBounded :: forall m n. (Typeable n, Integral n, Show n, Typeable m, Integral m, Bounded m, FiniteBits m) => n -> Result m
- data StrengthenFailure = StrengthenFailure {}
- failStrengthen1 :: [Builder] -> Result a
- failStrengthen :: [Builder] -> [(Builder, StrengthenFailure)] -> Result a
- type family Weak a :: Type
Strengthen class
class Weaken a => Strengthen a where Source #
Attempt to strengthen some Weak a
We take Weaken as a superclass in order to maintain strong/weak type pair
consistency. We choose this dependency direction because we treat the strong
type as the "canonical" one, so Weaken is the more natural (and
straightforward) class to define. That does mean the instances for this class
are a little confusingly worded. Alas.
See Strongweak for class design notes and laws.
Methods
strengthen :: Weak a -> Result a Source #
Attempt to strengthen some Weak aa.
Instances
restrengthen :: (Strengthen a, Weaken a) => a -> Result a Source #
Weaken a strong value, then strengthen it again.
Potentially useful if you have previously used
unsafeStrengthen and now wish to check the
invariants. For example:
>>>restrengthen $ unsafeStrengthen @(Vector 2 Natural) [0]Failure ...
type Result = Validation StrengthenFailure Source #
Helpers
strengthenBounded :: forall m n. (Typeable n, Integral n, Show n, Typeable m, Integral m, Bounded m, FiniteBits m) => n -> Result m Source #
Strengthen one numeric type into another.
n must be "wider" than m.
FiniteBits mShow nShow n
Strengthen failures
data StrengthenFailure Source #
A failure encountered during strengthening.
Constructors
| StrengthenFailure | |
Fields
| |
Instances
| Show StrengthenFailure Source # | |
Defined in Strongweak.Strengthen Methods showsPrec :: Int -> StrengthenFailure -> ShowS # show :: StrengthenFailure -> String # showList :: [StrengthenFailure] -> ShowS # | |
failStrengthen1 :: [Builder] -> Result a Source #
failStrengthen :: [Builder] -> [(Builder, StrengthenFailure)] -> Result a Source #
Re-exports
type family Weak a :: Type Source #
The weakened type for some type.