-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Type-indexed runtime-checked properties
--   
--   This package provides a (phantom) type-indexed newtype
--   evidence-wrapper for values that are checked to satisfy the property
--   associated with the type.
@package data-checked
@version 0.1


-- | Type-indexed runtime-checked properties.
module Data.Checked

-- | Wrapper-evidence for property <i>p</i>.
data Checked p v

-- | Use when the property can be deduced without a runtime check.
trustMe :: v -> Checked p v

-- | Unwrap the checked value.
checked :: Checked p v -> v
class Property p v
holds :: Property p v => p -> v -> Bool

-- | Return <a>Just</a> <i>v</i> if <i>p</i> holds and <a>Nothing</a>
--   overwise.
maybeHolds :: Property p v => p -> v -> Maybe v

-- | Wrap the value if the property holds.
check :: Property p v => v -> Maybe (Checked p v)