Operators are used to compute values from literals or variables and create expressions. Operators take one to three values and compute them with a grouping order and a priority level. Some operators can also be overridden in a user defined type.

Each operator has a priority level and a grouping order. It allows writing a full arithmetic expression and obtaining the expected result without describing the order of application of each operation.

The move assignment operators assign a value to a variable. It is used to initialize a variable or to change its value. Those operators do not work with types and can therefore not be overridden.

Those operators are not applicable to variables with a constant reference.

The copy assignment operator casts a value to the type of the value referenced by a variable and replaces the current value of the variable. Once replaced, any variables referencing this value will give the new value.

This operator can be overridden by user defined types to define how to cast the expression and change its value. If the type does not override this operator, it will only be applicable to values of the same type (because no cast method is defined) and will clone the value of each member of the object.

This operator is not applicable to the type package and to variables with a constant value.

The function call operator is mainly used to call functions. An expression list can be passed between the ( and ) operators. The number of expressions in the list will change the behavior of the operator and can eventually generate an error if the number is not handled. Many types can handle this operator and it can also be overridden by user defined types.

This operator is applicable to the following types:

• number, boolean: Create a constant copy of the value (takes no parameters)
• function: Call the function with the parameters
• object: Call the operator overload or create a constant copy of the object if not overloaded
• class: Create a new instance and call the new member with the parameters

The * operator can be used as a unary operator in a parameter list passed to a function call operator to expand each element contained in the value as an individual parameter.

Example:

var list = [0, 1, 2]
sum(*list) // is equivalent to sum(0, 1, 2)

The unpack operator can also be used to expand each element to initialize an array or an iterator.

Example:

// with myIterator = (3, 4, 5)
var list = [0, 1, 2, *myIterator, 6, 7, 8] // gives [0, 1, 2, 3, 4, 5, 6, 7, 8]

Arithmetic operators are used to perform mathematical operations like addition, subtraction, multiplication, etc.

Example:

15 + 4   // gives 19
15 - 4   // gives 11
15 * 4   // gives 60
15 / 4   // gives 3.75
15 % 4   // gives 3
15 ** 4  // gives 50625

Comparison operators are used to compare values. They return either true or false according to the condition. They are typically used by the control structures.

Example:

10 > 12   // gives false
10 < 12   // gives true
10 == 12  // gives false
10 != 12  // gives true
10 >= 12  // gives false
10 <= 12  // gives true

Logical operators are used to compare boolean values. They can also be overridden to apply the same behavior to user defined types.

Example:

true and false  // gives false
true or false   // gives true
not true        // gives false

Bitwise operators act on operands as if they were strings of binary digits. They operate bit by bit. They can also be overridden to apply the same behavior to user defined types.

Range operators create an iterator on a range of values. They can also be overridden to apply the same behavior to user defined types.

Example:

0..5   // gives (0, 1, 2, 3, 4, 5)
0...5  // gives (0, 1, 2, 3, 4)

Subscript operators are used to access a sub-element of a value. Sub-elements can be accessed for reading or for writing. A different behavior can be defined in both cases. They can also be overridden to apply the same behavior to user defined types.

Example:

a = ['a', 'b', 'c']

a[1]        // gives 'b'
a[1] = 'z'  // a gives now ['a', 'z', 'c']

Those operators are applicable to the following types:

• number: Access the digit at the given index
• function: Access the sub-function with the given number of parameters
• object: Access the sub-element associated with the given key/index

Search operators are used to search a sub-element of a value. This operator is meant to be used with conditional structures and its behavior can change depending on the kind of structure. To use this operator outside of a conditional structures, it must be used as a function. The in operator can also be overridden to search over a user defined types.

If the in operator is used in a for structure, it will return an iterator on each sub-element of the value. Each sub-element will be moved to the left part of the expression one after the other on each loop turn. The !in or not in operator cannot be used in a for structure.

If the in operator is used in an if or a while structure, it will return a boolean indicating whether the sub-element was found or not in the value. The !in or not in operator will invert the result of the in operator.

Example:

if 10 in 0..5 {
    // will never be executed
}

for i in 0..5 {
    // i gives 0 on the first turn, then 1, 2, 3, 4 and 5
}

(0..5).in(10)  // gives false
(0..5).in()    // gives (0, 1, 2, 3, 4, 5)

Match operators are commonly used to test a regex over an expression. They can also be overridden to apply the same behavior to user defined types.

Example:

/es/ =~ 'test'  // gives true
/es/ !~ 'test'  // gives false

The conditional operator evaluates an expression, returning one value if that expression gives true and a different one if the expression gives false.

Example:

defined a ? a : 0 // gives the value of a if a is defined; otherwise gives 0

Meta operators are used to get meta information on values.

The defined operator compares the value to none to check if the variable is defined. It can also check a full path to a member variable with only one expression.

Example:

defined foo.bar.member // equivalent to :
                       // not (foo is none) and not (foo.bar is none) and not (foo.bar.member is none)

The typeof operator provides the type of the value as a string.

Example:

typeof 0           // gives 'number'
typeof ''          // gives 'string'
typeof System.File // gives 'System.File'

The membersof operator provides the list of members of the value as an array of strings.

Example:

membersof ()  // gives [':=', 'each', 'isEmpty', 'next', 'value']