Data.Checked

Type-indexed runtime-checked properties.

Documentation

data Checked p v

Wrapper-evidence for property p.

Instances

Typeable2 Checked

NFData v => NFData (Checked p v)

trustMe :: v -> Checked p v

Use when the property can be deduced without a runtime check.

trustThat :: p -> v -> Checked p v

Use when the property can be deduced without a runtime check.

trustMap :: (v -> v) -> Checked p v -> Checked p v

Apply a fuction that preserves the property to the checked value.

checked :: Checked p v -> v

Unwrap the checked value.

class Property p v where

Methods

holds :: p -> v -> Bool

Test if the property holds for the given value. The first argument is supposed to be ignored.

maybeHolds :: Property p v => p -> v -> Maybe v

Return Just v if p holds and Nothing overwise.

check :: forall p v. Property p v => v -> Maybe (Checked p v)

Wrap the value if the property holds.