Function Statements

Function statements define reusable custom functions that can be called throughout your Trilogy scripts.

Syntax

function: "def" IDENTIFIER "(" function_binding_list ")" "->" expr
function_binding_item: IDENTIFIER function_binding_type? function_binding_default?
function_binding_type: ":" data_type
function_binding_default: "=" expr

Basic Function

Define a simple function:

def double(x) -> x * 2;

With Type Hints

Specify parameter types:

def calculate_tax(amount: float, rate: float) -> amount * rate;

With Default Values

Provide default parameter values:

def apply_discount(price, discount = 0.1) -> price * (1 - discount);

Calling Functions

Use @ prefix to call custom functions:

def format_currency(amount) -> concat('$', cast(round(amount, 2) as string));
select
    order.id,
    @format_currency(order.total) -> formatted_total
;

Complex Functions

Functions can use any expression:

def categorize_amount(amount) ->
    case
        when amount > 1000 then 'high'
        when amount > 100 then 'medium'
        else 'low'
    end;

Use Cases

• Reusable business logic
• Standardized calculations
• Code organization
• DRY principle

Example

# Define helper functions
def margin(revenue, cost) -> (revenue - cost) / revenue;
def growth_rate(current, previous) -> (current - previous) / previous * 100;
import order as order;
select
    order.product_id,
    sum(order.revenue) -> total_revenue,
    sum(order.cost) -> total_cost,
    @margin(total_revenue, total_cost) -> profit_margin
;