Operators

This page provides a complete reference for all operators in Tova, organized by category and including a full precedence table.

Arithmetic Operators

Operator	Name	Example	Result
+	Addition	3 + 4	7
-	Subtraction	10 - 3	7
*	Multiplication	4 * 5	20
/	Division	10 / 3	3.333...
%	Modulo	10 % 3	1
**	Power	2 ** 10	1024

For string concatenation, use + or string interpolation:

"hello" + " " + "world"   // "hello world"
"{first} {last}"           // string interpolation (preferred)

The * operator supports string repetition when used with a string and a number:

"-" * 40    // "----------------------------------------"
"abc" * 3   // "abcabcabc"

Unary - negates a number:

x = 42
y = -x     // -42

Comparison Operators

Operator	Name	Example
==	Equal	x == 10
!=	Not equal	x != 10
<	Less than	x < 10
<=	Less than or equal	x <= 10
>	Greater than	x > 10
>=	Greater than or equal	x >= 10

Chained Comparisons

Tova supports chained comparisons, which read naturally as mathematical inequalities:

1 < x < 10          // true when x is between 1 and 10 (exclusive)
0 <= score <= 100    // true when score is in [0, 100]
a < b < c < d        // true when a < b AND b < c AND c < d

Each intermediate value is evaluated only once. Chained comparisons desugar to a conjunction of pairwise comparisons.

Logical Operators

Tova provides both keyword and symbolic forms. The keyword forms are idiomatic:

Keyword	Symbol	Meaning	Example
and	&&	Logical AND	x > 0 and x < 10
or	||	Logical OR	x == 0 or x == 1
not	!	Logical NOT	not is_empty

Both forms are fully interchangeable:

// Keyword style (preferred)
if is_valid and not is_expired {
  process(item)
}

// Symbol style (also valid)
if is_valid && !is_expired {
  process(item)
}

Logical operators use short-circuit evaluation: and does not evaluate the right operand if the left is falsy, and or does not evaluate the right if the left is truthy.

Membership Operators

Operator	Meaning	Example
in	Contained in	"a" in list
not in	Not contained in	x not in banned

if item in allowed_items {
  accept(item)
}

if user not in banned_users {
  grant_access(user)
}

Type Checking Operators

Operator	Meaning	Example
is	Type check (true if value is of type)	x is String
is not	Negated type check	x is not Nil

The is operator tests the runtime type of a value. It works with built-in types and ADT variants:

value = "hello"
value is String       // true
value is Int          // false
value is not Nil      // true

// With ADT variants
result = Ok(42)
if result is Ok {
  print("Success!")
}

option = Some("data")
if option is not None {
  print("Has value")
}

Supported type checks: String, Int, Float, Bool, Nil, Array, Function, Number, and any custom ADT variant name.

Bitwise Operators

Operator	Name	Example
&	Bitwise AND	flags & mask
|	Bitwise OR	flags | FLAG_READ
^	Bitwise XOR	a ^ b
~	Bitwise NOT	~mask
<<	Left shift	1 << 4
>>	Right shift	n >> 2
>>>	Unsigned right shift	n >>> 1

// Bitwise operations
flags = 0b1010
mask = 0b1100

flags & mask     // 0b1000 (AND)
flags | mask     // 0b1110 (OR)
flags ^ mask     // 0b0110 (XOR)
~flags           // bitwise NOT
1 << 4           // 16 (left shift)
32 >> 2          // 8 (right shift)

Assignment Operators

Operator	Meaning	Equivalent
=	Assign	x = 10
+=	Add and assign	x = x + 10
-=	Subtract and assign	x = x - 10
*=	Multiply and assign	x = x * 10
/=	Divide and assign	x = x / 10
&=	Bitwise AND and assign	x = x & mask
|=	Bitwise OR and assign	x = x | flag
^=	Bitwise XOR and assign	x = x ^ bits
<<=	Left shift and assign	x = x << n
>>=	Right shift and assign	x = x >> n

var counter = 0
counter += 1       // counter is now 1
counter *= 5       // counter is now 5

Pipe Operator

The pipe operator |> passes the result of the left expression as the first argument to the function on the right:

// Without pipes
result = format(filter(map(data, transform), predicate))

// With pipes -- reads left to right
result = data
  |> map(transform)
  |> filter(predicate)
  |> format()

Placeholder _

Use _ as a placeholder to control where the piped value is inserted:

10 |> add(_, 5)         // add(10, 5)
"hello" |> replace(_, "l", "r")  // replace("hello", "l", "r")

Method Pipe

Use .method() syntax to call a method on the piped value:

items
  |> .filter(fn(x) x > 0)
  |> .map(fn(x) x * 2)
  |> .join(", ")

Range Operators

Operator	Name	Example	Meaning
..	Exclusive range	0..5	0, 1, 2, 3, 4
..=	Inclusive range	0..=5	0, 1, 2, 3, 4, 5

for i in 0..10 {       // 0 through 9
  print(i)
}

for i in 1..=100 {     // 1 through 100 (inclusive)
  print(i)
}

Spread Operator

The ... spread operator expands an iterable into individual elements:

a = [1, 2, 3]
b = [...a, 4, 5]       // [1, 2, 3, 4, 5]

opts = {color: "red"}
full = {...opts, size: 10}  // {color: "red", size: 10}

It also works in function calls:

args = [1, 2, 3]
sum(...args)            // sum(1, 2, 3)

Optional Chaining

The ?. operator accesses a property only if the receiver is not nil:

user?.address?.city     // nil if user or address is nil
items?.length           // nil if items is nil

Nil Coalescing

The ?? operator returns the left operand if it is not nil, otherwise the right:

name = user?.name ?? "Anonymous"
port = config?.port ?? 3000

Member Access and Subscript

Operator	Name	Example
.	Member access	user.name
[]	Subscript / index	items[0]

point.x                 // access field x
matrix[0][1]            // nested indexing
map["key"]              // string subscript

Fat Arrow and Thin Arrow

Operator	Name	Usage
=>	Fat arrow	Match arms, route handlers, short lambdas
->	Return type	Function return type annotations

// Fat arrow in match
match status {
  200 => "OK"
  404 => "Not Found"
  _ => "Unknown"
}

// Thin arrow for return types
fn add(a: Int, b: Int) -> Int {
  a + b
}

Error Propagation Operator

The ? postfix operator unwraps a Result or Option, returning early if it contains an error or absence:

fn process(input: String) -> Result<Data, String> {
  parsed = parse(input)?           // returns Err early if parse fails
  validated = validate(parsed)?    // returns Err early if validation fails
  Ok(validated)
}

? on a Result returns the Err value from the enclosing function. ? on an Option returns None. See the Error Handling guide for details.

Await and Yield Operators

The await prefix operator suspends execution until an async expression resolves:

result = await fetch_data(url)

The yield prefix operator produces a value from a generator function. Any function containing yield is automatically treated as a generator — no special syntax is needed. Use yield from to delegate to another generator:

fn range_gen(start, end) {
  for i in start..end {
    yield i
  }
}

fn combined() {
  yield from range_gen(1, 5)
  yield from range_gen(10, 15)
}

Both await and yield have the same precedence as unary - and ... (spread).

Other Operators

Operator	Name	Usage
:	Type annotation / object field	x: Int, {name: "Alice"}
::	Slice step (inside [] only)	items[::2], items[1::3]
++	String prefix matching (in match patterns only)	"api/" ++ rest
?	Error propagation	parse(input)?

Operator Precedence

Operators are listed from highest precedence (binds tightest) to lowest (binds loosest). Operators on the same row have equal precedence.

Level	Operators	Associativity	Description
17	. ?. [] () ?	Left	Member access, optional chain, subscript, call, error propagation
16	- (unary) ... (spread) await yield	Right	Unary negation, spread, await, yield
15	**	Right	Exponentiation
14	* / %	Left	Multiplication, division, modulo
13	+ -	Left	Addition, subtraction
12	<< >> >>>	Left	Bitwise shift
11	.. ..=	None	Range (exclusive, inclusive)
10	in not in is is not	None	Membership test, type checking
9	< <= > >= == !=	Left	Comparison (chainable)
8	&	Left	Bitwise AND
7	^	Left	Bitwise XOR
6	|	Left	Bitwise OR
5	not ! ~	Right	Logical NOT, bitwise NOT
4	and &&	Left	Logical AND
3	or ||	Left	Logical OR
2	??	Left	Null coalescing
1	|>	Left	Pipe

Precedence Examples

// Unary - binds tighter than **
-2 ** 3          // (-2) ** 3 = -8
-2 ** 2          // (-2) ** 2 = 4  (not -(2 ** 2) = -4)

// * binds tighter than +
2 + 3 * 4        // 2 + (3 * 4) = 14

// and binds tighter than or
a or b and c     // a or (b and c)

// |> has lowest precedence
data |> f() |> g()  // g(f(data))

// ?? binds tighter than |> but looser than or
a ?? b |> f()    // f(a ?? b)