Clause

interface Clause: Struct, Any

Fields

Name Description
open functor: String
abstract head: Struct?
abstract body: Term
abstract isWellFormed: Boolean

Checks whether this Clause is wellFormed

A Clause is said to be "well formed" if:

  • its head isn't a Numeric or a Var
  • its body isn't a Numeric and doesn't contain a Numeric in arguments place, for notable Structs with functors ','/2, ';'/2 and '->'/2
open args: Array<Term>
open arity: Int
open isClause: Boolean

Checks whether the current term is a clause, i.e., either a rule or a directive. This method is guaranteed to return true if and only if the current term is an instance of Clause.

open isRule: Boolean

Checks whether the current term is a rule, or a fact. This method is guaranteed to return true if and only if the current term is an instance of Rule.

open isFact: Boolean

Checks whether the current term is a fact. This method is guaranteed to return true if and only if the current term is an instance of Fact.

open isDirective: Boolean

Checks whether the current term is a directive. This method is guaranteed to return true if and only if the current term is an instance of Directive.

Methods

freshCopy

open fun freshCopy(): Clause

Returns a fresh copy of this Term, that is, an instance of Term which is equal to the current one in any aspect, except variables directly or indirectly contained into this Term, which are refreshed. This means that it could return itself, if no variable is present (ground term), or a new Term with freshly generated variables.

Variables are refreshed consistently, meaning that, if more variables exists within this Term having the same name, all fresh copies of such variables will have the same complete name.

Example: "f(X, g(X))".freshCopy() returns something like "f(X_1, g(X_1))" instead of "f(X_1, g(X_2))"

Notice that, if the current term is ground, the same object may be returned as a result by this method.

ReturnValue

Name Description
Clause

a fresh copy of the current term which is different because variables are consistently renamed

freshCopy

open fun freshCopy(scope: Scope): Clause

Returns a fresh copy of this Term, similarly to freshCopy, possibly reusing variables from the provided scope, if any

Parameters

Name Description
scope: Scope

the Scope containing variables to be used in copying

ReturnValue

Name Description
Clause

a fresh copy of the current term which is different because variables are consistently renamed

Extensions

prepareForExecution

fun Clause.prepareForExecution(): Clause

Prepares the receiver Clause for execution, using the provided visitor

For example, the Clause product(A) :- A, A is transformed, after preparation for execution, as the Term: product(A) :- call(A), call(A)

Receiver

Name Description
Clause

ReturnValue

Name Description
Clause

prepareForExecution

fun Clause.prepareForExecution(unifier: Unifier): Clause

Receiver

Name Description
Clause

Parameters

Name Description
unifier: Unifier

ReturnValue

Name Description
Clause

extractSignature

fun Struct.extractSignature(): Signature

Extracts this Struct indicator and converts it to Signature

Receiver

Name Description
Struct

ReturnValue

Name Description
Signature

unfoldGoals

fun Term.unfoldGoals(): Sequence<Term>

Receiver

Name Description
Term

ReturnValue

Name Description
Sequence<Term>

toGoals

fun Term.toGoals(): Cursor<Term>

Receiver

Name Description
Term

ReturnValue

Name Description
Cursor<Term>

isWellFormed

fun Term.isWellFormed(): Boolean

Check whether the receiver term is a well-formed predication

Receiver

Name Description
Term

ReturnValue

Name Description
Boolean

prepareForExecutionAsGoal

fun Term.prepareForExecutionAsGoal(): Struct

Prepares the receiver Goal for execution

For example, the goal A is transformed, after preparation for execution, as the Term: call(A)

Receiver

Name Description
Term

ReturnValue

Name Description
Struct

eq

infix fun Term.eq(that: Term): Equation<Term, Term>

Creates an equation with this and that terms

Receiver

Name Description
Term

Parameters

Name Description
that: Term

ReturnValue

Name Description
Equation<Term, Term>

CompanionObject

Clause

interface Clause: Struct, Any

Fields

Name Description
const FUNCTOR: String
val notableFunctors: /** Contains notable functor in determining if a Clause [isWellFormed] */

Contains notable functor in determining if a Clause isWellFormed

val bodyWellFormedVisitor: TermVisitor<Boolean>

A visitor that checks whether isWellFormed (body constraints part) is respected

Methods

of

fun of(head: Struct?, vararg body: Term): Clause

Parameters

Name Description
head: Struct?
vararg body: Term

ReturnValue

Name Description
Clause