Types & Safety

A type defines the structure of data and the operations permitted on it. Kyna validates types at compile time so type errors are caught early.

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Primitive Types

Kyna provides five core primitive types:

Type	Description	Example Literal
int	Signed 64-bit integers	42, -10, 0x2A
float	Double-precision 64-bit floating point numbers	3.14159, -0.5
str	UTF-8 encoded Unicode strings	"Hello, world", "Kyna"
bool	Boolean logical values	true, false
null	Absence of a value	null

var count: int = 100;
var price: float = 19.99;
var name: str = "Production Server";
var isRunning: bool = true;

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Type Inference

Writing explicit type annotations is optional for initialized variables. Kyna infers the tightest possible static type automatically:

var port = 8080;         # Inferred as 'int'
var active = true;       # Inferred as 'bool'
var host = "127.0.0.1";  # Inferred as 'str'

# port = "8080";         # Compile error: cannot assign 'str' to 'int'

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Explicit Null Safety (T?)

In Kyna, standard types cannot hold null. To allow a variable or return value to be null, mark its type with ?:

# Non-nullable: guaranteed never to be null
var name: str = "Alice";
# name = null; # Compile error: cannot assign null to non-nullable type 'str'

# Nullable: can hold either a string or null
var alias: str? = null;
alias = "Alicia"; # Valid

Safe Type Narrowing

When you perform a null check with if (val != null), the compiler automatically narrows the type from T? to T inside the conditional block:

fn greet(nickname: str?) {
    if (nickname != null) {
        # 'nickname' is narrowed to 'str' (non-nullable) here
        print("Hello, " + nickname);
    } else {
        print("Hello, anonymous guest");
    }
}

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Collections (list and map)

Kyna provides built-in typed collections for sequential arrays and associative dictionaries:

# Lists (homogeneous sequences)
var endpoints = ["/health", "/metrics", "/v1/users"];
print("Primary endpoint:", endpoints[0]);
print("Total count:", len(endpoints));

# Maps (key-value dictionaries)
var config = {
    "host": "localhost",
    "port": "5432",
    "ssl": "enabled"
};

print("Connecting to:", config["host"]);

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Numeric Polymorphism (num)

When writing generic mathematical functions that should accept either int or float, use the num supertype:

fn multiply(a: num, b: num): num {
    return a * b;
}

print(multiply(4, 5));       # 20 (int)
print(multiply(2.5, 4.0));   # 10.0 (float)

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The any Escape Hatch

For dynamic interoperability or deserialization of arbitrary JSON payloads, Kyna provides the any type:

var dynamicPayload: any = jsonParse("{\"status\": 200}");

info

Kyna never silently widens variables to any. You must explicitly declare any to disable static type checks.

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Next Steps

• Explore Operators & Expressions.
• Master Control Flow & Pattern Matching.