Lorentz.Test.DupableScan

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

Documentation

type family CheckDupablesDistribution a where ...

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)

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 ()

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

A term-level version of VerifyDupablesDistribution for tests.

data BadElement

Error for checkDupablesDistribution.

Constructors

BadElement

Fields

• beExpectedDupability :: Bool
• beRecName :: Maybe Text
• beRecType :: TypeRep

Instances

Show BadElement

Defined in Lorentz.Test.DupableScan

Methods

showsPrec :: Int -> BadElement -> ShowS

show :: BadElement -> String

showList :: [BadElement] -> ShowS

Eq BadElement

Defined in Lorentz.Test.DupableScan

Methods

(==) :: BadElement -> BadElement -> Bool

(/=) :: BadElement -> BadElement -> Bool

Buildable BadElement

Defined in Lorentz.Test.DupableScan

Methods

build :: BadElement -> Doc

buildList :: [BadElement] -> Doc