Version 2 (modified by Chuck, 13 years ago)


class Example

   def main is shared

   def bill(customers as Customer*)
      for c in customers

   def foo(ints as int*)
      t = for i in ints where i > 0
      print t

   def bar(ints as int*)
      t = List<of int>(t)
      print t
  • The general form of a stream type is "foo*" where "foo" is the element type.
  • The "*" suffix can be thought of as "zero or more".
  • The type "foo*" can be read as "foo stream".
  • Streams can be applied to both primitive and complex types such as "int*" and "Shape*".
  • Streams are portable between backends, whereas .NET's IEnumerable<of> and JVM's Iterable<of> are not.
  • Streams are two-way compatible with IEnumerable/Iterable:
    • Streams can be used whereever a compatible IEnumerable/Iterable is expected.
    • An IEnumerable/Iterable can be used whereever a compatible stream type is expected.
    • The term "compatible" means the same inner type: int* is compatible with IEnumerable<of int>/Iterable<of int>, but not IEnumerable<of String>/Iterable<of String>
      • However, compatibility does not mean that you can use the methods of IEnumerable or Iterable, since these vary between platforms.
  • Streams are an abstract type, so you cannot create them directly with a call on the type such as int*(). Instead, use a concrete class such as List<of> or yield results out of a method.
  • Streams are defaulted to be empty rather than nil.
  • Portability and readability are the main motivations for having streams in the Cobra language.
  • See also:  "Streams" discussion