Moduledata-checked-0.3Haskell98

Data.Checked

Type-indexed runtime-checked properties.

Synopsis

newtypenewtype Checked p v

Wrapper-evidence for property p.

Instances1NFData

valuetrustMe :: v -> Checked p v

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

valuetrustThat :: p -> v -> Checked p v

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

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

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

valuechecked :: Checked p v -> v

Unwrap the checked value.

classclass Property p v where

holds :: p -> v -> Bool
Test if the property holds for the given value. The first argument is supposed to be ignored.

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

Return Just v if p holds and Nothing overwise.

valuecheck :: Property p v => v -> Maybe (Checked p v)

Wrap the value if the property holds.