Name Rascal/Libraries/Prelude/Type

Synopsis This is a module that reflects Rascal's type system, implemented in Rascal itself.

Usage import Type;

Details Attr choice comparable eq equivalent Exception glb isADTType isAliasType isBagType isBoolType isConstructorType isDateTimeType isFunctionType isIntType isListRelType isListType isLocType isMapType isNodeType isNumType isRatType isRealType isReifiedType isRelType isSetType isStrType isTupleType isTypeVar isValueType isVoidType lub make Production subtype Symbol typeOf var-func

Description The goal of this module is to provide:

• reflection capabilities that are useful for deserialization and validation of data, and
• to provide the basic building blocks for syntax trees (see ParseTree)
  
  The following definition is built into Rascal:

• data type[&T] = type(Symbol symbol, map[Symbol,Production] definitions);

The # operator will always produce a value of type[&T], where &T is bound to the type that was reified.

The following functions are provided on types:

• Attr: Attributes register additional semantics annotations of a definition.
• choice: Choice between alternative productions.
• comparable: Check if two types are comparable, i.e., have a common supertype.
• eq: structural equality between values.
• equivalent: Check if two types are equivalent.
• Exception:
• glb: The greatest lower bound (glb) between two types.
• isADTType: Determine if the given type is an Abstract Data Type (ADT).
• isAliasType: Determine if the given type is an alias.
• isBagType: Determine if the given type is a bag (bags are not yet implemented).
• isBoolType: Determine if the given type is a bool.
• isConstructorType: Determine if the given type is a constructor.
• isDateTimeType: Determine if the given type is a datetime.
• isFunctionType: Determine if the given type is a function.
• isIntType: Determine if the given type is an int.
• isListRelType: Determine if the given type is a list relation.
• isListType: Determine if the given type is a list.
• isLocType: Determine if the given type is a loc.
• isMapType: Determine if the given type is a map.
• isNodeType: Determine if the given type is a node.
• isNumType: Determine if the given type is a num.
• isRatType: Determine if the given type is a rational.
• isRealType: Determine if the given type is a real.
• isReifiedType: Determine if the given type is a reified type.
• isRelType: Determine if the given type is a relation.
• isSetType: Determine if the given type is a set.
• isStrType: Determine if the given type is a string.
• isTupleType: Determine if the given type is a tuple.
• isTypeVar: Determine if the given type is an type variable (parameter).
• isValueType: Determine if the given type is a value.
• isVoidType: Determine if the given type is a void.
• lub: The least-upperbound (lub) between two types.
• make: instantiate an ADT constructor of a given type with the given children
• Production: A production in a grammar or constructor in a data type.
• subtype:
• Symbol: A Symbol represents a Rascal Type.
• typeOf: returns the dynamic type of a value as a reified type
• var-func:

Examples

rascal>#int
type[int]: type(
  int(),
  ())
rascal>#rel[int,int]
type[rel[int,int]]: type(
  rel([
      int(),
      int()
    ]),
  ())
rascal>data B = t();
ok
rascal>#B
type[B]: type(
  adt(
    "B",
    []),
  (adt(
      "B",
      []):choice(
      adt(
        "B",
        []),
      {cons(
          label(
            "t",
            adt(
              "B",
              [])),
          [],
          [],
          (),
          {})})))
rascal>syntax A = "a";
ok
rascal>#A;
type[sort("A")]: type(
  sort("A"),
  (
    layouts("default"):choice(
      layouts("default"),
      {prod(
          layouts("default"),
          [],
          {})}),
    empty():choice(
      empty(),
      {prod(
          empty(),
          [],
          {})}),
    sort("A"):choice(
      sort("A"),
      {prod(
          sort("A"),
          [lit("a")],
          {})})
  ))
rascal>type(\int(),())
type[value]: type(
  int(),
  ())

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