hlt.language.design.types

Class TypeDefinition

java.lang.Object

hlt.language.design.types.TypeTermScheme

hlt.language.design.types.TypeDefinition

public class TypeDefinition
extends TypeTermScheme

This class encapsulates the information associated to a type term acting as an alias (or synonym) of another type.

An object of this class consists of a (type) name, possibly along with some type parameters if it is polymorphic, and associated with a type defining it. Such type definitions are not opaque: the type terms are fully expanded into the definition they stand for and disappear altogether once this is done. In other words, using a this construct is paramount to using a shorthand notation; importantly, it does not create a new type. Thus, its purpose is simply to offer a syntactic convenience that may be used to enhance program legibility. Once defined with an object of this class, a type term with this name (possibly with type arguments if this definition is polymorphic) can be used anywhere a type is expected.

If what is sought is an opaque type definition, then what is needed is a DefinedType.

At any rate, look in Tables for the methods that will define a type alias (DefineTypeAlias(...)) or a new opaque type (DefineNewType(...)).

See Also:

DefinedType, Tables

Method Summary

Methods

Modifier and Type	Method and Description
Type	definition() Returns a fresh copy of the type defining this definition's type term.
Type	instantiate(java.util.AbstractList types) Returns a fresh copy of the type definition instantiated with the specified types.
java.lang.String	toString()

Methods inherited from class hlt.language.design.types.TypeTermScheme

arity, parameters

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

definition

public final Type definition()

Returns a fresh copy of the type defining this definition's type term.

instantiate

public final Type instantiate(java.util.AbstractList types)
                       throws StaticSemanticsErrorException

Returns a fresh copy of the type definition instantiated with the specified types. It checks that the arities correspond. If no parameters exist for this definition but the type instances have a positive arity, an array of parameters is created with this arity. This is necessary in order to enforce that all instances of this type have the same arity.

Throws:

StaticSemanticsErrorException

toString

public final java.lang.String toString()

Overrides:

toString in class java.lang.Object