Qaqao Syntax

2.2 Semantic Syntax

2.1.1 Qaqao Top-Level Script Elements

Qaqao_compiler_script ::

Sequential_list{Qaqao_script_message}

Qaqao_script_message ::

Import_message

Export_message

Interface_message

Implement_message

Import_message ::

Tuple [“import” Concurrent_list (Tuple [“objects” ‘«’ Concurrent_list (Identifier)] | Tuple [“packages” ‘«’ Concurrent_list (Identifier)])]

The outer list must contain one or two elements: a single tuple beginning with the string “objects”, and/or a single tuple beginning with the string “packages”.

Export_message ::

Tuple [“export” Concurrent_list (Tuple [“objects” ‘«’ Concurrent_list (Simple-identifier)] | Tuple [“to-packages” ‘«’ Concurrent_list (Identifier)])]

The outer list must contain exactly two elements: a single tuple beginning with the string “objects” and a single tuple beginning with the string “to-packages”.

Interface_message ::

Tuple [“interface” Concurrent_list (Tuple [“declarations” ‘«’ Concurrent_list (Declaration_statement)])]

The outer list must contain exactly one element: a single tuple beginning with the string “declarations”.

Implement_message ::

Tuple [“implement” Concurrent_list (Tuple [“declarations” ‘«’ Concurrent_list (Declaration_statement)] | Tuple [“definitions” ‘«’ Concurrent_list (Definition_statement)])]

The outer list must contain one or two elements: an optional tuple beginning with the string “declarations”, and a single tuple beginning with the string “definitions”.

Definition_statement ::

Tuple [“define” Bound_expression “as” Statement]

2.1.2 Qaqao Statements

Statement ::

Declaration_statement

Binding_statement

Send_statement

Receive_statement

SendReceive_statement

Local_statement

Sequential_statement

Concurrent_statement

If_statement

Case_statement

Loop_statement

ForEach_statement

ForAll_statement

BreakFromLoopIf_statement

Declaration_statement ::

Tuple [Declarative_expression Simple_expression]

Binding_statement ::

Tuple [Bound_expression ‘«’ Expression]

Send_statement ::

Tuple [Bound_expression ‘←’ Bound_expression]

Receive_statement ::

Tuple [Expression ‘→’ Bound_expression]

SendReceive_statement ::

Tuple [Bound_expression ‘←’ Bound_expression ‘→’ Bound_expression]

Local_statement ::

Tuple [“local” Statement]

Sequential_statement ::

Sequential_list {Statement}

Concurrent_statement ::

Concurrent_list (Statement)

If_statement ::

Tuple [“if” Simple_expression “thenDo” Statement
(“elseIf” Simple_expression “thenDo” Statement)*
(“elseDo” Statement)?]

Case_statement ::

Tuple [“case” Simple_expression “of”
Concurrent_list (Tuple [“when” Concurrent_list (Simple_expression) “do” Statement])
(“elseDo” Statement)?]

Loop_statement ::

Tuple [“loop” Sequential_statement]

ForEach_statement ::

Tuple [“forEach” Simple_identifier “in” Expression “do” Statement]

ForAll_statement ::

Tuple [“forAll” Simple_identifier “in” Expression “do” Statement]

BreakFromLoopIf_statement ::

Tuple [“breakFromLoopIf” Simple_expression]

NOTE: A BreakFromLoopIf statement is only allowed in the body of a Loop or a ForEach statement. At least one such statement must occur in the body of every Loop statement, outside the body of any nested loop (including ForAll loops.

2.1.3 Qaqao Expressions

Expression ::

Declarative_expression

Bound_expression

Send_expression

Let_expression

Sequence_expression

Vector_expression

If_expression

Case_expression

ForEach_expression

ForAll_expression

Infix_expression

Statement

Simple_expression ::

Declarative_expression

Bound_expression

Send_expression

Let_expression

If_expression

Case_expression

Infix_expression

Declaration_expression ::

Tuple [Declarative_expression Simple_expression]

Send_expression ::

Tuple [Bound_expression ‘←’ Bound_expression]

Let_expression ::

Tuple [“let” Statement “in” Expression]

Sequence_expression ::

Sequential_list {Expression}

Vector_expression ::

Concurrent_list (Expression)

If_expression ::

Tuple [“if” Simple_expression “then” Expression
(“elseIf” Simple_expression “then” Expression)*
“else” Expression]

Case_expression ::

Tuple [“case” Simple_expression “of”
Concurrent_list (Tuple [“when” Concurrent_list (Simple_expression) “yield” Expression])
“elseYield” Expression]

ForEach_expression ::

Tuple [“forEach” Simple_identifier “in” Expression “yield” Expression]

ForAll_expression ::

Tuple [“forAll” Simple_identifier “in” Expression “yield” Expression]

Infix_expression ::

Tuple [Operator* Expression (Operator+ Expression)*]

Declarative_expression ::

Identifier

Declarative_parameter_expression

Declarative_parameter_expression ::

Tuple [Simple_identifier Concurrent_list (Parameter_declaration_expression)]

Parameter_declaration_expression ::

Tuple [Simple_identifier Simple_expression (“default” Expression)?]

Bound_expression ::

Identifier

Bound_parameter_expression

Bound_parameter_expression ::

Tuple [Simple_identifier Concurrent_list (Parameter_binding_Expression)]

Parameter_binding_expression ::

Tuple [Simple_identifier ‘«’ Expression]

Identifier ::

Simple_identifier

Compound_identifier

2.1.4 Infix Expressions

Standard Qaqao Operators

Category	Operator	Unicode	Operation	Associativity
Parenthetical	⌈ ⌉ ⌊ ⌋ ⟨ ⟩	&u+2308 &u+2309 &u+230A &u+230B &u+2329 &u+232A	ceiling floor absolute value	parenthetical
Sign	−	&u+2212	negate	prefix
Exponential	↑	&u+2191	exponentiate	right
Multiplicative	× ÷ %	&u+00D7 &u+00F7 &u+0025	multiply divide remainder	left
Additive	+ −	&u+002B &u+2212	add subtract	left
Shifting	↞ ↠	&u+219E &u+21A0	shift left shift right	left
Comparative	≡ = ≠ < ≤ > ≥	&u+2261 &u+003D &u+2260 &u+003C &u+2264 &u+003E &u+2265	identical to equal to not equal to less than less than or equal to greater than greater than or equal to	none
Negative	¬	&u+00AC	not	prefix
Conjunctive	∧	&u+2227	and	left
Disjunctive	∨	&u+2228	or	left

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Qaqao Language Definition, section 2.2, version 0.34α

© J. Andrew Holey, 2009

email: jholey@csbsju.edu