propellor-5.13: property-based host configuration management in haskell

Safe Haskell | None
Language | Haskell2010

Propellor.EnsureProperty

Synopsis

- ensureProperty :: EnsurePropertyAllowed inner outer => OuterMetaTypesWitness outer -> Property (MetaTypes inner) -> Propellor Result
- property' :: SingI metatypes => Desc -> (OuterMetaTypesWitness metatypes -> Propellor Result) -> Property (MetaTypes metatypes)
- data OuterMetaTypesWitness metatypes
- type family EnsurePropertyAllowed inner outer :: Constraint where ...

# Documentation

ensureProperty :: EnsurePropertyAllowed inner outer => OuterMetaTypesWitness outer -> Property (MetaTypes inner) -> Propellor Result Source #

For when code running in the Propellor monad needs to ensure a Property.

Use `property`` to get the `OuterMetaTypesWithness`. For example:

    foo = Property Debian
    foo = property' "my property" $ \w -> do
    	ensureProperty w (aptInstall "foo")

The type checker will prevent using ensureProperty with a property that does not support the target OSes needed by the OuterMetaTypesWitness. In the example above, aptInstall must support Debian, since foo is supposed to support Debian.

The type checker will also prevent using ensureProperty with a property with HasInfo in its MetaTypes. Doing so would cause the `Info` associated with the property to be lost.

property' :: SingI metatypes => Desc -> (OuterMetaTypesWitness metatypes -> Propellor Result) -> Property (MetaTypes metatypes) Source #

Constructs a property, like `property`, but provides its `OuterMetaTypesWitness`.

data OuterMetaTypesWitness metatypes Source #

Used to provide the metatypes of a Property to calls to `ensureProperty` within it.

type family EnsurePropertyAllowed inner outer :: Constraint where ... Source #

Equations

EnsurePropertyAllowed inner outer = 'True ~ (EnsurePropertyNoInfo inner && EnsurePropertyTargetOSMatches inner outer) |