Safe Haskell	Safe-Inferred
Language	Haskell2010

Lorentz.Test.DupableScan

Description

Test utilities to ensure the proper layout of non-dupable elements within datatypes.

Synopsis

type family CheckDupablesDistribution a where ...
type VerifyDupablesDistribution a = ResToConstraint (CheckDupablesDistribution a)
checkDupablesDistribution :: forall a. DemoteRes (CheckDupablesDistribution a) => Either BadElement ()
testDupablesDistribution :: forall a. (Typeable a, DemoteRes (CheckDupablesDistribution a)) => TestTree
data BadElement = BadElement {
- beExpectedDupability :: Bool
- beRecName :: Maybe Text
- beRecType :: TypeRep
}

Documentation

type family CheckDupablesDistribution a where ... Source #

For the given type, check that at the left subtree of pairs tree it contains only dupable elements, and at the right - only non-dupable ones.

On ambiguity, evaluation is delayed to avoid exposing Generic internals.

Equations

CheckDupablesDistribution ThisTypeShallNotBeExported = TypeError ('Text "impossible")
CheckDupablesDistribution a = GCheckDupablesDistribution (GRep a)

type VerifyDupablesDistribution a = ResToConstraint (CheckDupablesDistribution a) Source #

A constraint that, for the given type, checks that at the left subtree of pairs tree it contains only dupable elements, and at the right - only non-dupable ones.

checkDupablesDistribution :: forall a. DemoteRes (CheckDupablesDistribution a) => Either BadElement () Source #

CheckDupablesDistribution for term-level.

Shows decent error messages on missing Generic instance.

>>> checkDupablesDistribution
...
... Ambiguous type variable ‘a0’ arising from a use of ‘checkDupablesDistribution’
... prevents the constraint ‘(Lorentz.Test.DupableScan.DemoteRes
... (CheckDupablesDistribution a0))’ from being solved.
...

The type must have a Generic instance.

>>> data Foo = Foo () (Ticket ())
>>> checkDupablesDistribution @Foo
...
... GHC.Generics.Rep Foo
... is stuck. Likely
... Generic Foo
... instance is missing or out of scope.
...

The type itself needn't necessarily have IsoValue instance, but all its leaves must.

>>> data Foo = Foo () (Ticket ()) deriving Generic
>>> checkDupablesDistribution @Foo
Right ()

testDupablesDistribution :: forall a. (Typeable a, DemoteRes (CheckDupablesDistribution a)) => TestTree Source #

A term-level version of VerifyDupablesDistribution for tests.

data BadElement Source #

Error for checkDupablesDistribution.

Constructors

BadElement
Fields beExpectedDupability :: Bool beRecName :: Maybe Text beRecType :: TypeRep

Instances

Instances details

Show BadElement Source #
Instance details Defined in Lorentz.Test.DupableScan Methods showsPrec :: Int -> BadElement -> ShowS # show :: BadElement -> String # showList :: [BadElement] -> ShowS #
Eq BadElement Source #
Instance details Defined in Lorentz.Test.DupableScan Methods (==) :: BadElement -> BadElement -> Bool # (/=) :: BadElement -> BadElement -> Bool #
Buildable BadElement Source #
Instance details Defined in Lorentz.Test.DupableScan Methods build :: BadElement -> Doc buildList :: [BadElement] -> Doc