Chapel Language Specification Version 0.984 Cray Inc 901 Fifth Avenue, Suite 1000 Seattle, WA 98164 October 5, 2017 c 2017 Cray Inc. Contents 1 Scope 13 2 Notation 14 3 Organization 16 4 Acknowledgments 18 5 Language Overview 19 5.1 Guiding Principles . 19 5.1.1 General Parallel Programming . 19 5.1.2 Locality-Aware Programming . 20 5.1.3 Object-Oriented Programming . 20 5.1.4 Generic Programming . 21 5.2 Getting Started . 21 6 Lexical Structure 22 6.1 Comments . 22 6.2 White Space . 22 6.3 Case Sensitivity . 22 6.4 Tokens . 22 6.4.1 Identifiers . 23 6.4.2 Keywords . 23 6.4.3 Literals . 24 6.4.4 Operators and Punctuation . 26 6.4.5 Grouping Tokens . 27 7 Types 28 7.1 Primitive Types . 28 7.1.1 The Void Type . 29 7.1.2 The Bool Type . 29 7.1.3 Signed and Unsigned Integral Types . 29 7.1.4 Real Types . 30 7.1.5 Imaginary Types . 30 7.1.6 Complex Types . 30 7.1.7 The String Type . 30 7.2 Enumerated Types . 31 7.3 Structured Types . 32 7.3.1 Class Types . 32 7.3.2 Record Types . 32 7.3.3 Union Types . 32 7.3.4 Tuple Types . 32 7.4 Data Parallel Types . 33 7.4.1 Range Types . 33 7.4.2 Domain, Array, and Index Types . 33 7.5 Synchronization Types . 33 3 Chapel Language Specification 4 7.6 Type Aliases . 34 8 Variables 35 8.1 Variable Declarations . 35 8.1.1 Default Initialization . 36 8.1.2 Deferred Initialization . 37 8.1.3 Local Type Inference . 37 8.1.4 Multiple Variable Declarations . 37 8.2 Module Level Variables . 38 8.3 Local Variables . 39 8.4 Constants . 39 8.4.1 Compile-Time Constants . 39 8.4.2 Runtime Constants . 40 8.5 Configuration Variables . 40 8.6 Ref Variables . 40 9 Conversions 42 9.1 Implicit Conversions . 42 9.1.1 Implicit Numeric, Bool and Enumeration Conversions . 43 9.1.2 Implicit Compile-Time Constant Conversions . 44 9.1.3 Implicit Statement Bool Conversions . 44 9.2 Explicit Conversions . 44 9.2.1 Explicit Numeric Conversions . 44 9.2.2 Explicit Tuple to Complex Conversion . 45 9.2.3 Explicit Enumeration Conversions . 45 9.2.4 Explicit Class Conversions . 46 9.2.5 Explicit Record Conversions . 46 9.2.6 Explicit Range Conversions . 46 9.2.7 Explicit Domain Conversions . 46 9.2.8 Explicit Type to String Conversions . 47 10 Expressions 48 10.1 Literal Expressions . 49 10.2 Variable Expressions . 49 10.3 Enumeration Constant Expression . 49 10.4 Parenthesized Expressions . 49 10.5 Call Expressions . 50 10.6 Indexing Expressions . 50 10.7 Member Access Expressions . 50 10.8 The Query Expression . 50 10.9 Casts . 51 10.10 LValue Expressions . 51 10.11 Precedence and Associativity . 52 10.12 Operator Expressions . 54 10.13 Arithmetic Operators . 54 10.13.1 Unary Plus Operators . 55 10.13.2 Unary Minus Operators . 55 10.13.3 Addition Operators . 56 10.13.4 Subtraction Operators . 57 10.13.5 Multiplication Operators . ..