Built-in Functions

Althread provides several built-in functions for common operations.

print(...) - Display

Displays the arguments passed as parameters to the console.

Signature:

print(arg1, arg2, ..., argN) -> void
print(arg1 + arg2 + ... + argN) -> void

Parameters:

• Accepts a variable number of arguments of any type
• Arguments can be separated by commas , or concatenated with +
• With commas: arguments are separated by spaces in the output
• With the + operator: arguments are concatenated directly

Example:

main {
    let x = 42;
    let name = "Althread";
    
    // With commas (separated by spaces)
    print("Hello world!");                     // Displays: Hello world!
    print("x =", x);                          // Displays: x = 42
    print("Language:", name, "version", 1.0); // Displays: Language: Althread version 1.0
    
    // With the + operator (direct concatenation)
    print("x = " + x);                        // Displays: x = 42
    print("Language: " + name + " version " + 1.0); // Displays: Language: Althread version 1.0
}

---

assert(condition, message) - Verification

Verifies that a condition is true. If the condition is false, the program stops with an error message.

Signature:

assert(condition: bool, message: string) -> void

Parameters:

• condition: Boolean expression to verify
• message: Error message to display if the condition is false

Example:

shared {
    let X: int = 0;
}

program A() {
    X++;
}

program B() {
    X--;
}

main {
    atomic {
        run A();
        run B();
    }
    
    assert(X == 0, "X should be equal to 0");
    assert(X < 1, "X must be less than 1");
}

Usage with local variables:

program Calculator() {
    let result = 10 / 2;
    assert(result == 5, "Incorrect division");
    
    let list: list(int);
    list.push(1);
    list.push(2);
    assert(list.len() == 2, "The list should contain 2 elements");
}

Recommended usage

assert() is particularly useful for:

• Verifying system invariants
• Testing program behavior
• Validating conditions after complex operations

Program termination

If an assertion fails, the program stops immediately and displays the error message. Use assert() only for critical verifications.