Penny.Steel.Pdct

Trees of predicates.

Exports names which conflict with Prelude names, so you probably want to import this module qualified.

Documentation

data Pdct a

A tree of predicates.

Constructors

Pdct Label (Node a)

Instances

Show (Pdct a)

always :: Pdct a

Returns a tree that is always True.

never :: Pdct a

Returns a tree that is always False.

and :: [Pdct a] -> Pdct a

or :: [Pdct a] -> Pdct a

not :: Pdct a -> Pdct a

operand :: Text -> (a -> Bool) -> Pdct a

Creates a new operand. The Pdct is Just True or Just False, never Nothing.

neverFalse :: Pdct a -> Pdct a

Turns an existing Pdct to one that never says False. If the underlying predicate returns Just True, the new Pdct also returns Just True. Otherwise, the Pdct returns Nothing. Has no effect on non-Operand Pdct.

neverTrue :: Pdct a -> Pdct a

Turns an existing Pdct to one that never says True. If the underlying predicate returns Just False, the new Pdct also returns Just False. Otherwise, the Pdct returns Nothing. Has no effect on non-Operand Pdct.

(&&&) :: Pdct a -> Pdct a -> Pdct a

(|||) :: Pdct a -> Pdct a -> Pdct a

type Level = Int

type IndentAmt = Int

type ShowDiscards = Bool

showPdct :: IndentAmt -> Level -> Pdct a -> [Chunk]

rename :: (Text -> Text) -> Pdct a -> Pdct a

Renames the top level of the Pdct. The function you pass will be applied to the old name.

eval :: Pdct a -> a -> Maybe Bool

Evaluates a Pdct.

evaluate

Arguments

:: IndentAmt

Indent each level by this many spaces.

-> ShowDiscards

If True, show discarded test results; otherwise, hide them.

-> a

The subject to evaluate

-> Level

How many levels deep in the tree we are. Start at level 0. This determines the level of indentation.

-> Pdct a

-> (Maybe Bool, [Chunk])

Verbosely evaluates a Pdct.

boxPdct :: (b -> a) -> Pdct a -> Pdct b

Given a function that un-boxes values of type b, changes a Pdct from type a to type b.

boxNode :: (b -> a) -> Node a -> Node b

Given a function that un-boxes values of type b, changes a Node from type a to type b.