rewriting-0.2: Generic rewriting library for regular datatypes. Source code Contents Index

Generics.Regular.Rewriting.Rules Portability non-portable Stability experimental Maintainer generics@haskell.org

Contents Rule specification. Representation of a rule. Builder for transforming a rule specification to a rule.

Description

Summary: Functions for transforming a rule specification to a rule.

Synopsis

data RuleSpec a = a :~> a lhsR :: RuleSpec a -> a rhsR :: RuleSpec a -> a type Rule a = RuleSpec (SchemeOf a) type SchemeOf a = Scheme (PF a) type Metavar = Int metavar :: Metavar -> Scheme f pf :: f (Scheme f) -> Scheme f toScheme :: (Regular a, Functor (PF a)) => a -> SchemeOf a data SchemeView f = Metavar Metavar | PF (f (Scheme f)) schemeView :: Scheme f -> SchemeView f foldScheme :: Functor f => (Metavar -> a) -> (f a -> a) -> Scheme f -> a class Regular (Target a) => Builder a where type Target a :: * base :: a -> RuleSpec (Target a) diag :: a -> [RuleSpec (Target a)] ruleM :: (Builder r, CrushR (PF (Target r)), Zip (PF (Target r)), Functor (PF (Target r))) => r -> Maybe (Rule (Target r)) rule :: (Builder r, CrushR (PF (Target r)), Functor (PF (Target r)), Zip (PF (Target r))) => r -> Rule (Target r)

Rule specification.

data RuleSpec a Source

Specifies a rule as a value of a datatype. Constructors a :~> a Instances Regular a => Builder (RuleSpec a)

lhsR :: RuleSpec a -> a Source

Returns the left-hand side of a rule.

rhsR :: RuleSpec a -> a Source

Returns the right-hand side of a rule.

Representation of a rule.

type Rule a = RuleSpec (SchemeOf a) Source

Allows metavariables on either side of a rule.

type SchemeOf a = Scheme (PF a) Source

Extends the pattern functor of a value.

type Metavar = Int Source

metavar :: Metavar -> Scheme f Source

Constructs a metavariable.

pf :: f (Scheme f) -> Scheme f Source

Constructs a pattern functor value.

toScheme :: (Regular a, Functor (PF a)) => a -> SchemeOf a Source

Recursively converts a value to a SchemeOf value.

data SchemeView f Source

A view on schemes to easily distinguish metavariables from pattern functor values. Constructors Metavar Metavar PF (f (Scheme f))

schemeView :: Scheme f -> SchemeView f Source

Returns the value corresponding to the SchemeView.

foldScheme :: Functor f => (Metavar -> a) -> (f a -> a) -> Scheme f -> a Source

Folds a Scheme value given a function to apply to metavariables and a function to apply to a pattern functor value.

Builder for transforming a rule specification to a rule.

class Regular (Target a) => Builder a where Source

The type class Builder captures the functions, that are defined by induction on the type argument, that construct appropriate left and right values. These values are used to transform a rule specification to a rule. Associated Types type Target a :: * Source Methods base :: a -> RuleSpec (Target a) Source diag :: a -> [RuleSpec (Target a)] Source Instances Regular a => Builder (RuleSpec a) (Builder a, Regular b, LR (PF b)) => Builder (b -> a)

ruleM :: (Builder r, CrushR (PF (Target r)), Zip (PF (Target r)), Functor (PF (Target r))) => r -> Maybe (Rule (Target r)) Source

Transforms a rule specification to a rule and returns Nothing if an unbound metavariable occurs in the right-hand side of the rule.

rule :: (Builder r, CrushR (PF (Target r)), Functor (PF (Target r)), Zip (PF (Target r))) => r -> Rule (Target r) Source

Transforms a rule specification to a rule and throws a runtime error if an unbound metavariable occurs in the right-hand side of the rule.

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