wyil.lang

Interface Type

All Known Subinterfaces:

Type.Array, Type.EffectiveArray, Type.EffectiveRecord, Type.EffectiveReference, Type.Function, Type.FunctionOrMethod, Type.Intersection, Type.Leaf, Type.Method, Type.Negation, Type.Nominal, Type.Primitive, Type.Property, Type.Record, Type.Reference, Type.Union

All Known Implementing Classes:

Type.Impl, Type.Impl.Atom, Type.Impl.Conjunctable, Type.Impl.Function, Type.Impl.FunctionOrMethod, Type.Impl.Method, Type.Impl.PositiveAtom, Type.Impl.Primitive, Type.Impl.Property

public interface Type

A structural type. See http://whiley.org/2011/03/07/implementing-structural-types/ for more on how this class works.

Author:

David J. Pearce

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	Type.Array An array type describes array values whose elements are subtypes of the element type.
static interface	Type.EffectiveArray An effective array is a type which looks like an array, but is not exactly an array.
static interface	Type.EffectiveRecord An effective record is a type which looks like a record, but is not exactly a record.
static interface	Type.EffectiveReference An effective reference is a type which looks like an reference, but is not exactly an reference.
static interface	Type.Function Represents the set of all function values.
static interface	Type.FunctionOrMethod Represents the set of all functions or methods.
static class	Type.Impl
static interface	Type.Intersection Represents the intersection of one or more types together.
static interface	Type.Leaf Represents a type which constitutes a "leaf" node in the type tree.
static interface	Type.Method Represents the set of all method values.
static interface	Type.Negation Represents the set of types which are not in a given type.
static interface	Type.Nominal Represents a named type within the system.
static interface	Type.Primitive Represents a primitive type (e.g.
static interface	Type.Property Represents the set of all proeprty values.
static interface	Type.Record A record is made up of a number of fields, each of which has a unique name.
static interface	Type.Reference Represents a reference to an object in Whiley.
static interface	Type.Union Represents the union of one or more types together.

Field Summary

Fields

Modifier and Type	Field and Description
static Type	T_ANY The type any represents the type whose variables may hold any possible value.
static Type	T_BOOL Represents the set of boolean values (i.e.
static Type	T_BYTE Represents a sequence of 8 bits.
static Type	T_INT Represents the set of (unbound) integer values.
static Type	T_META The type meta represents the type of types.
static Type	T_NULL The null type is a special type which should be used to show the absence of something.
static Type	T_VOID A void type represents the type whose variables cannot exist! That is, they cannot hold any possible value.

Method Summary

Modifier and Type	Method and Description
static Type	Array(Type element)
static Type	fromString(String str)
static Type	Function(Type[] parameters, Type[] returns)
static Type	Intersection(Type... types) Construct the intersection of one or more types together.
static Type	Method(Collection<String> lifetimeParameters, Collection<String> contextLifetimes, Type[] parameters, Type[] returns)
static Type	Method(String[] lifetimeParameters, String[] contextLifetimes, Type[] parameters, Type[] returns)
static Type	Method(Type[] parameters, Type[] returns)
static Type	Negation(Type type) Construct the negation of a given type.
static Type	Nominal(wybs.lang.NameID name)
static Type	Property(Type[] parameters)
static Type	Record(boolean isOpen, List<wycc.util.Pair<Type,String>> fields)
static Type	Record(boolean isOpen, wycc.util.Pair<Type,String>... fields)
static Type	Reference(String lifetime, Type element)
static wyil.lang.Type.Impl.Array[]	toImplArrays(Type.Impl[] types)
static Type.Impl[]	toImplOrVoid(Type[] types)
static wyil.lang.Type.Impl.Record[]	toImplRecords(Type.Impl[] types)
static Type	Union(Type... types) Construct the union of one or more types together.

Field Detail

T_ANY

static final Type T_ANY

The type any represents the type whose variables may hold any possible value. NOTE: the any type is top in the type lattice.

T_VOID

static final Type T_VOID

A void type represents the type whose variables cannot exist! That is, they cannot hold any possible value. Void is used to represent the return type of a function which does not return anything. However, it is also used to represent the element type of an empty list of set. NOTE: the void type is a subtype of everything; that is, it is bottom in the type lattice.

T_NULL

static final Type T_NULL

The null type is a special type which should be used to show the absence of something. It is distinct from void, since variables can hold the special null value (where as there is no special "void" value). With all of the problems surrounding null and NullPointerExceptions in languages like Java and C, it may seem that this type should be avoided. However, it remains a very useful abstraction to have around and, in Whiley, it is treated in a completely safe manner (unlike e.g. Java).

T_BOOL

static final Type T_BOOL

Represents the set of boolean values (i.e. true and false)

T_BYTE

static final Type T_BYTE

Represents a sequence of 8 bits. Note that, unlike many languages, there is no representation associated with a byte. For example, to extract an integer value from a byte, it must be explicitly decoded according to some representation (e.g. two's compliment) using an auxillary function (e.g. Byte.toInt()).

T_INT

static final Type T_INT

Represents the set of (unbound) integer values. Since integer types in Whiley are unbounded, there is no equivalent to Java's MIN_VALUE and MAX_VALUE for int types.

T_META

static final Type T_META

The type meta represents the type of types. That is, values of this type are themselves types. (think reflection, where we have class Class {}).

Method Detail

Nominal

static Type Nominal(wybs.lang.NameID name)

Record

static Type Record(boolean isOpen,
                   List<wycc.util.Pair<Type,String>> fields)

Record

static Type Record(boolean isOpen,
                   wycc.util.Pair<Type,String>... fields)

Array

static Type Array(Type element)

Reference

static Type Reference(String lifetime,
                      Type element)

Function

static Type Function(Type[] parameters,
                     Type[] returns)

Property

static Type Property(Type[] parameters)

Method

static Type Method(Type[] parameters,
                   Type[] returns)

Method

static Type Method(Collection<String> lifetimeParameters,
                   Collection<String> contextLifetimes,
                   Type[] parameters,
                   Type[] returns)

Method

static Type Method(String[] lifetimeParameters,
                   String[] contextLifetimes,
                   Type[] parameters,
                   Type[] returns)

toImplOrVoid

static Type.Impl[] toImplOrVoid(Type[] types)

toImplArrays

static wyil.lang.Type.Impl.Array[] toImplArrays(Type.Impl[] types)

toImplRecords

static wyil.lang.Type.Impl.Record[] toImplRecords(Type.Impl[] types)

Negation

static Type Negation(Type type)

Construct the negation of a given type. This operation performs certain simplifications to ensure types are in a manageable form. For example, the negation of a negation is just the element type. Likewise, the negation of a union is an intersection of negations, etc.

Parameters:

types -

Returns:

Union

static Type Union(Type... types)

Construct the union of one or more types together. This operation performs certain simplifications to ensure types are in a manageable form. For example, the union of one type is that type. Likewise, the union of two identical types is just one type, etc. NOTE this operation assumes free access to modify the given array

Parameters:

types -

Returns:

Intersection

static Type Intersection(Type... types)

Construct the intersection of one or more types together. This operation performs certain simplifications to ensure types are in a manageable form. For example, the intersection of one type is that type. Likewise, the intersection of two identical types is just one type, etc. NOTE this operation assumes free access to modify the given array

Parameters:

types -

Returns:

fromString

static Type fromString(String str)