Operators

BoxLang provides symbolic and word operators for calculations, comparisons and control flow.

Arithmetic and strings

Use + for arithmetic and & for joining text. Numeric strings can participate in arithmetic: "5" + "6" is 11. Division by zero throws an error.

Comparison and logic

println( 5 == 5 );
println( 5 eq 5 );
println( 5 neq 4 );
println( 5 != 4 );
println( 3 lte 3 );
println( 3 gte 4 );
println( "a" < "b" );
println( 1 is 1 );
println( "abc" contains "B" );
println( "abc" does not contain "x" );
println( true && false || true );
println( true and false );
println( true xor false );
println( 1 eqv 1 );
println( !false );

Output:

true
true
true
true
true
false
true
true
true
true
true
false
true
true
true

String comparison ignores case: "a" == "A" is true. === behaves like ==, which BoxLang does too.

Use ! or not for negation, && or and for conjunction, and || or or for alternatives.

Bitwise

BoxLang spells bitwise operators with a b prefix.

println( 5 b& 3 );
println( 5 b| 3 );
println( 5 b^ 3 );
println( b~ 5 );
println( 1 b<< 4 );
println( 256 b>> 4 );
println( 16 b>>> 2 );

Output:

1
7
6
-6
16
16
4

Both operands must be numbers.

castAs and instanceOf

castAs takes the type name as a string. Wrap it in parentheses when you combine it with other operators, because the string after castAs swallows what follows.

println( ( 5 castAs "string" ) & "!" );
println( ( "3.5" castAs "numeric" ) + 1 );
println( "yes" castAs "boolean" );
println( "a" instanceOf "string" );
println( 1 instanceOf "numeric" );
println( { } instanceOf "struct" );
println( [ ] instanceOf "array" );
println( ( x => x ) instanceOf "function" );
println( 1 instanceOf "string" );

Output:

5!
4.5
true
true
true
true
true
true
false

• "abc" castAs "numeric" throws BoxCastException: Could not cast object [abc] to type [numeric].
• 7.9 castAs "integer" throws a BoxCastException. BoxLang does too.
• x castAs string without quotes fails.
• setValue instanceOf "set" is false for a set.

Elvis, ternary and safe navigation

n = null;
println( n ?: "was null" );
println( "" ?: "not used" );
println( 5 > 3 ? "yes" : "no" );

s = { a: { b: 2 } };
println( s?.a?.b );
println( s.missing?.deeper ?: "safe" );
println( isNull( n?.a ) );

Output:

was null

yes
2
safe
true

?: only replaces null. An empty string passes through, so the second line prints an empty line.

A ?. guards only the step it is on. n?.a.b with n null throws Member access only supported on structs, instances, JS objects, and native objects. BoxLang returns null. Write n?.a?.b.

For sets and ranges see sets and destructuring, spread and ranges.