Unbound.PermM

A slow, but hopefully correct implementation of permutations.

Documentation

data Perm a

Instances

Ord a => Eq (Perm a)

Show a => Show (Perm a)

Ord a => Monoid (Perm a)

single :: Ord a => a -> a -> Perm a

compose :: Ord a => Perm a -> Perm a -> Perm a

Compose two permutations. The right-hand permutation will be applied first.

apply :: Ord a => Perm a -> a -> a

support :: Ord a => Perm a -> [a]

isid :: Ord a => Perm a -> Bool

isid -- do all keys map to themselves?

join :: Ord a => Perm a -> Perm a -> Maybe (Perm a)

Join two permutation. Fail if the two permutations map the same name to two different variables.

empty :: Perm a

restrict :: Ord a => Perm a -> [a] -> Perm a

mkPerm :: Ord a => [a] -> [a] -> Maybe (Perm a)

mkPerm l1 l2 creates a permutation that sends l1 to l2. Fail if there is no such permutation, either because the lists have different lengths or because they are inconsistent (which can only happen if l1 or l2 have repeated elements).