Operators

Table

The table below contains the operators in NPL, the equivalent method name, a short explanation, an example, and a precedence level (where 1 indicates the highest precedence).

Most operators can be also expressed using a functional syntax, for example 2.plus(3) is the same as 2 + 3.

Operator	Method name	Explanation	Example	Precedence	Operates on
=	N/A	assignment	= expr	1	any value
!	not	logical complement (not)	!expr	2	Boolean
-	negative	arithmetic negation	-expr	2	Number, Amount
*	multiplyBy	arithmetic multiplication	expr * expr	3	Number and Number, Amount and Number
/	divideBy	arithmetic division	expr / expr	3	Number and Number, Amount and Number
%	remainder	arithmetic division remainder	expr % expr	3	Number and Number, Amount and Number
+	plus	arithmetic addition	expr + expr	4	Number and Number, Amount and Amount
+	plus	concatenation	expr + expr	4	Text and Text, List and List, Set and Set
+	plus	time addition	expr + expr	4	DateTime and Duration, DateTime and Period
-	minus	arithmetic subtraction	expr - expr	4	Number and Number, Amount and Amount
-	minus	time subtraction	expr - expr	4	DateTime and Duration, DateTime and Period
>	greaterThan	greater than comparison	expr > expr	5	Number and Number, Text and Text
>=	greaterThanOrEqual	greater than or equal to comparison	expr >= expr	5	Number and Number, Text and Text
<	lessThan	less than comparison	expr < expr	5	Number and Number, Text and Text
<=	lessThanOrEqual	less than or equal to comparison	expr <= expr	5	Number and Number, Text and Text
==	N/A	equality comparison	expr == expr	6	any two values
!=	N/A	inequality comparison	expr != expr	6	any two values
&&	N/A	logical and	expr && expr	7	Boolean and Boolean
||	N/A	logical or	expr || expr	8	Boolean and Boolean

Equality

Equality comparisons for types that hold other types, such as Optional and collections, and performed element-wise. While this makes equality comparisons compatible with unions, it also means that in some cases types with different type parameters may be considered equal.

Given

union U { Number, Text }

the following are all true

optionalOf<Number>(1) == optionalOf<U>(1)

optionalOf<Number>()  == optionalOf<U>()

optionalOf<Number>()  == optionalOf<Text>()

Remainder

The remainder operator (%) supports negative dividend and divisor. The sign of the divisor does not affect the result. The sign of the result is the same as the sign of the dividend. The following examples illustrate this.

47 % 10,
47 % -10,
7 // all equal

-47 % 10,
-47 % -10,
-7 // all equal

50 % 10,
50 % -10,
-50 % 10,
-50 % -10,
0 // all equal

5.8 % 2.2,
5.8 % -2.2,
1.4 // all equal

-5.8 % 2.2,
-5.8 % -2.2,
-1.4 // all equal

Operator context

Each operator's meaning in the context of types is described with the type. Parties have their own operators, and are described in party expressions.