Functions¶

AISL supports user-defined functions for organizing reusable logic.

Defining functions¶

Functions are declared using the declare ... as function syntax:

declare FUNCTION_NAME as function(PARAM1, PARAM2, ...) {
    // function body
}

Parameters are positional identifiers separated by commas. The function body is a block of one or more statements.

declare add as function(a, b) {
    return a + b;
}

declare evaluate_model as function(model, question, context) {
    let result = query_model(model, question, context);
    let value = get(result, "value");
    return value;
}

Functions can have no parameters:

declare get_threshold as function() {
    return 0.9;
}

Calling functions¶

Functions are called by name with arguments in parentheses:

let sum = add(3, 5);
let threshold = get_threshold();
let value = evaluate_model(my_model, "Is AI safe?", {"topic": "safety"});

Arguments are evaluated left-to-right and passed by value to the corresponding parameters.

Variable scope in functions¶

Each function call creates a new local scope. Variables assigned with let inside a function body are local to that invocation and do not affect the global scope. The local scope has access to global variables for reading, but writing creates a local shadow.

let x = 10;

declare double_x as function() {
    let x = x * 2;  // local x, shadows global
    return x;
}

let result = double_x();  // 20
// global x is still 10

Return values¶

Functions return a value in one of two ways:

1. Explicit return: Using a return statement.

   declare square as function(n) {
       return n * n;
   }
   

2. Implicit return: If no return statement is reached, the function returns the last value computed on the evaluation stack.

Recursion¶

Functions can call themselves recursively:

declare factorial as function(n) {
    let result = n == 1 ? 1 : n * factorial(n - 1);
    return result;
}

Built-in functions¶

AISL includes over 40 built-in functions for metrics, statistics, data operations, and LLM queries. These are always available without declaration. See the Built-in Functions section for a complete reference.

Built-in functions are called with the same syntax as user-defined functions:

let avg = mean([1, 2, 3, 4, 5]);
let acc = accuracy(y_true, y_pred);
let parsed = parse_json(response_text);