Data.Rewriting.Substitution

Documentation

data GSubst v f v'

A generalised? substitution: a finite, partial map from variables to terms with a different variable type.

Instances

(Pretty f, Pretty v) => Pretty (Subst f v)

(Show v, Show f, Show v') => Show (GSubst v f v')

(Pretty v, Pretty f, Pretty v') => Pretty (GSubst v f v')

type Subst f v = GSubst v f v

A substitution, mapping variables to terms. Substitutions are equal to the identity almost everywhere.

Important operations

gApply :: Ord v => GSubst v f v' -> Term f v -> Maybe (Term f v')

Apply a substitution, assuming that it's total. If the term contains a variable not defined by the substitution, return Nothing.

apply :: Ord v => Subst f v -> Term f v -> Term f v

Apply a substitution, assuming that it's the identity on variables not mentionend in the substitution.

compose :: Ord v => Subst f v -> Subst f v -> Subst f v

Compose substitutions. We have

 (s1 `compose` s2) `apply` t = s1 `apply` (s2 `apply` t).

Reexported modules

module Data.Rewriting.Substitution.Type

module Data.Rewriting.Substitution.Ops

module Data.Rewriting.Substitution.Match

module Data.Rewriting.Substitution.Unify

module Data.Rewriting.Substitution.Pretty

module Data.Rewriting.Substitution.Parse