Informal Opal Specification

Opal is meant to bring together the three primary styles, object-oriented, procedural, and functional. Some of its features are suited to only one of these styles, note will be made where this is the case. Since Opal is first and foremost an object-oriented language, that is the approach that will be taken in this document. The appendix contains information on how the other styles may wish to view Opal's support of them, but also give important criteria about the meaning of certain constructs.

• Introduction
  • What is Opal?
  • What Opal is not
  • Conventions
  • Named vs. Anonymous
  • Spatial & Temporal
  • Fundamental Features
  • ASAP Garbage Collection
  • Syntax
  
  
• 1. Lexical Specification
  • 1.1 Whitespace
  • 1.2 Comments
  • 1.3 Identifiers
  • 1.4 Keywords
  • 1.5 Reserved Words
  • 1.6 Operators & Separators
  • 1.7 Primitive Literals
    • 1.7.1 Boolean Literals
    • 1.7.2 Character Literals
    • 1.7.3 Integer Literals
    • 1.7.4 Floating Point Literals
    • 1.7.5 Array Literals
    • 1.7.6 String Literals
  
  
• 2. Entities
  
  • 2.1 Access Modifiers
  • 2.2 Entity Names
    • 2.2.1 Entity Name Overloading
  • 2.3 Super Type
  • 2.4 Interface Types
  • 2.5 Entity Values
  
  
• 3. Objects
  • 2.1 Named Objects
    • 2.1.1 Anonymous Types
    • 2.1.2 Creation Code
    • 2.1.3 Destruction Blocks
    • 2.1.4 Named Types
  • 2.2 Anonymous Objects
    • 2.2.1 Object Literals
    • 2.2.2 Conversion Expressions
  
  
• 4. Patterns
  • 4.1 Pattern Parameters
  • 4.2 Named Patterns
    • 4.2.1 Anonymous Types
    • 4.2.2 Returning Self
    • 4.2.3 Pattern Types
    • 4.2.4 Named Types
    • 4.2.5 Pattern Overloading
  • 4.3 Anonymous Patterns
    • 4.3.1 Pattern Literals
    • 4.3.3 Pattern Conversion Expressions
  
  
• 5. Inheritance
  • 5.1 Type Compatibility
  • 5.2 Super Type
  • 5.3 Virtual Patterns
  • 5.4 Abstract Patterns
  • 5.5 Interfaces
  • 5.6 Implementing Interfaces
  
  
• 6. Statements & Expressions
  • 6.1 Expressions
    • 6.1.1 Names
    • 6.1.2 Member Selection
    • 6.1.3 Literal Expressions
    • 6.1.4 Invocation
    • 6.1.5 Assignment
    • 6.1.6 Conversion Expressions
    • 6.1.7 Grouping Expressions
  • 6.2 Statements
    • 6.2.1 Return Statement
  
  
• 7. Scoping
  • 7.1 Lexical Containment
  • 7.2 Access Modifiers
    • 7.2.1 Public
    • 7.2.2 Scope
    • 7.2.3 Protected
    • 7.2.4 Private
    • 7.2.5 Personal
  • 7.3 Name Lookup
  • 7.4 Pseudonyms
    • 7.4.1 Self Keyword
    • 7.4.2 This Keyword
    • 7.4.3 Super Keyword
    • 7.4.4 Outer Keyword
  
  
• 8. Invariants
  • 8.1 Final
    • 8.1.1 Final Named Types
    • 8.1.2 Final & Virtual
    • 8.1.3 Final Patterns
  • 8.2 Const
    • 8.2.1 Const Properties
    • 8.2.2 Const Methods
    • 8.2.3 Const Classes
    • 8.2.4 Const Objects
  • 8.3 Mutable
  
  
• 9. Exceptions
  • 9.1 Throw Statements
  • 9.2 Throws Clauses
  • 9.3 Try Catch Statements
  
  
• 10. Parametric Polymorphism


• 11. Object Forms
  • 11.1 Modules
    • 11.1.1 Import Statements
  • 11.2 Properties
  • 11.3 Methods
    • 11.3.1 Functions
    • 11.3.2 Default Parameters
  • 11.4 Classes
    • 11.4.1 Class Keyword
    • 11.4.2 Create Methods
  • 11.5 Interfaces
  
  
• 12. Extras
  • 12.1 Blocks
  • 12.2 Operators
    • 12.2.1 Operator Precedence
    • 12.2.2 Operator Overloading
    • 12.2.3 This Parameter
    • 12.2.4 Accept ( '..' ) Operator
    • 12.2.5 Arithmetic Operators
    • 12.2.6 Assignment Operators
    • 12.2.7 Bitwise Operators
    • 12.2.8 Comparison Operators
    • 12.2.9 IO Operators
    • 12.2.10 Logical Operators
    • 12.2.11 Member Selection ( '.' ) Operator
    • 12.2.12 Sequencing and Grouping Operators
    • 12.2.13 Subscripting ( '[]' ) Operator
  • 12.3 Flow control
    • 12.3.1 If-Else
    • 12.3.2 Switch
    • 12.3.3 While and Do-While
    • 12.3.4 For
    • 12.3.5 Break
    • 12.3.6 Continue
    • 12.3.7 Return
    • 12.3.8 Yield
  
  
• 13. Primitives and Literals
  • 13.1 Object
  • 13.2 Class
  • 13.3 Void
  • 13.4 Boolean
  • 13.5 Characters
  • 13.6 Integers
  • 13.7 Reals
  • 13.8 Lists and Tuples
    • List and Tuple Literals
  • 13.9 Arrays
    • Array Literals
  • 13.10 Strings
    • String Literals
  
  
• 14. Procedural Features
  • Pointers
  • References
  • Local Values
  
  
• 15. Odds and Ends
  • 15.1 ASAP Garbage Collection
  • 15.2 Modifier Ordering
  • 15.3 Pattern Contents
  • 15.4 Tail Calls
  • 15.5 Warnings
  
  
• 16. Formal Syntax
  • 16.1 Lexical Structure
  • 16.2 Syntactic Structure