Function Call

OQL allows one to call an OQL function with or without parameters. The operator for function call is ().
A function call may be the first term of a path expression, for instance: first(select Person)->name.
Contrary to the method invocation, there are no function overloading mechanisms: that means, that one cannot have differents functions with the same name and a different signature. To take benefit of the overloading mechanisms, one must use methods.
Note: contrary to the ODMG 3 specifications, one currently needs to use parenthesis to invoke a method even if the method has no arguments.

General Information
Operator	()
Syntaxe	expr (expr_list)
Type	n-ary
Operand Types	first operand: identifier, other operands: any type
Returned type	type of the returned atom by the function call
Functions	calls the OQL function denoted by the first operand using the other operands as arguments. The number of operands must be equal to the number of arguments of the OQL function plus one

Expression Examples
expression	result
fact(10)	3628800
fact(fact(3))	720
toUpper("hello world")	"HELLO WORLD"
toUpper("hello") + "world"	"HELLOworld"
interval(1, 5)	list(1, 2, 3, 4, 5)
swap(&i, &j)	nil
first(select Person).spouse.name	"mary"