Data.Iso.Core

Partial isomorphisms

data Iso a b

Bidirectional partial isomorphism.

Constructors

Iso (a -> Maybe b) (b -> Maybe a)

Instances

Category Iso

Monoid (Iso a b)

Semigroup (Iso a b)

convert :: Iso a b -> a -> Maybe b

Apply an isomorphism in one direction.

inverse :: Iso a b -> Iso b a

Inverse of an isomorphism.

many :: Iso a a -> Iso a a

Apply an isomorphism as many times as possible, greedily.

Stack-based isomorphisms

data h :- t

Heterogenous stack with a head and a tail.

Constructors

h :- t

Instances

(Eq h, Eq t) => Eq (:- h t)

(Show h, Show t) => Show (:- h t)

stack :: Iso a b -> Iso (a :- t) (b :- t)

Convert to a stack isomorphism.

unstack :: Iso (a :- ()) (b :- ()) -> Iso a b

Convert from a stack isomorphism.

swap :: Iso (a :- (b :- t)) (b :- (a :- t))

Swap the top two arguments.

duck :: Iso t1 t2 -> Iso (h :- t1) (h :- t2)

Introduce a head value that is passed unmodified.

lit :: Eq a => a -> Iso t (a :- t)

Push or pop a specific value.

inverseLit :: Eq a => a -> Iso (a :- t) t

Inverse of lit.

matchWithDefault :: (a -> Bool) -> a -> Iso t (a :- t)

When converting from left to right, push the default value on top of the stack. When converting from right to left, pop the value, make sure it matches the predicate and then discard it.

ignoreWithDefault :: a -> Iso t (a :- t)

When converting from left to right, push the default value on top of the stack. When converting from right to left, pop the value and discard it.